C Programming from Scratch

1. 1 Introduction: Hello and welcome this new course in which we will teach you C programming for beginners. This is actual form educational engineering team. Learning C programming will help you get career all change your career path. You can become a better developer and you must know that c is the number one programming language in the world. You might know Python. Python is based on C programming. And you can look this up using any search engine. In this new course, you will learn C programming from scratch. We'll start with the basics of C programming. Let's talk about conditional statements, NC. After that, we will cover loops, different types of loops like while for and do-while. And we will take examples. We'll talk about C functions and arrays. Then we'll move to more advanced topics like pointers that are modifiers, datatypes, Nc. At the end we will have our processor directives and dynamic memory allocation. Each of these sections will have more than five assignments. Last two quizzes to make sure that you understand each of these aspects will give you examples. And we'll do examples together, which is basically a practical coding exercises. And there'll be a homework. I'm sure that at the end of this course, you will understand the fundamentals of the C programming language. And you can easily create C codes. You will learn how to create even your own library in C. We'll also cover how to apply. See in real time programming, projects, problems, and functions. You will learn how to write high-quality code in no time and you will learn the best programming or C programming practices. This is a comprehensive course that will be updated in weekly basis. We will follow up with our students, answer their questions and help them with the assignments. Of this course, there will be a project that you must do, NC to make sure that you understand everything we explained during this course. Thanks for watching this introduction. See you inside. 2. Download and Install C Editor and Compiler: Hello and welcome this annulus all in which we are going to download and install the software that we will use to write codes in this course. Now they're out of software that you can use to write C codes. But the one that we will start with, the one that we would like you to start with is called Notepad Plus, Plus. As you can see, it's basically a notepad. Simply click the Download and choose the latest version. Choose depending on your operating system. As you can see, Support for almost all of the operating systems. Simply hit the Download button. And you'll download will start. Now click once to start the installation process. Choose your language. Click Okay. Now click Next. Click, I agree. Next, Next. And you can create a shortcut on the desktop. Then click Install. Won't take long. It's a very small software, simply lived on and hit the finished pattern. Now here we will write our sequence. Now in this white area, you can choose the language that you are writing for from that language, drop-down menu. Simply go to C and select C. Now, you are good to go regarding writing codes, but we also need to compile our code. In order to combine the codes, we need to use a compiler called GCC compiler. So again, go to google.com. And in here, right, GCC compiler. As you can see, GCC compiler collection. You can open it up. And here you will find a lot of information and resources about this compiler. This compile includes front ends for C, C plus plus Objective C, Fortran, other goal, and D, as well as libraries for other languages. Now, you can select any of these versions. But let's finish, feels overwhelming for a lot of people. So we will go with direct installer. So go back to Google and write glenn GW C compiler. Once you like that, you will see that we have sourceforge.net.EXE file that we can download and install. And we also have the original site called Men GW dash W 64, that all this is it. Now you can go to the download section, make sure that you are inside this website. Once you're inside the download section, scroll down until you reach this point. Men, WOW, 64 builds running for Windows. The support C, C plus plus fortran. Click once. And here you will find that installation location. As you can see, men GW builds. Click on the source fall. And here it is. Now, make sure that you are installing the software from dislocation source for this name. Click once. Click Yes. Now click Next. Leave it to the default. Click Next, change the location. We need it to be inside the sea directory and leave. Everything is as it is. C, D w dash, W 64, slash or backslash. Now click Next. Now make sure that you normalize dislocation. Click Next. And it will start downloading and installation of the compiler files. Now there are other options to write C codes, but this is the first one, and we'll explain all of them in this section. Now, you are free to choose which one you want to go with. Now once you are done, click Next and Finish. Now, if you went to that original folder in which all of the files were sold, it's inside our C directory. As you can see here. And here we have the main GW. As you can see. Here, we have the flat file. This is the original file that we need. We need the bin folder. So make sure that you are inside this folder. See mainly WOW, 64, when GW 32. Click once and right-click, then copy. Now we need to make windows understand that we have a C compiler installed. Now, you need to go to your desktop, right-click on your PC. Select probabilities. Now, select advanced system settings. And from this window you can select environment variables. You will see this list. Go to the system variables down here. Scroll until you reach the path, then hit the edit button. Now, this cell is too fast. And what we need to do is to add a new path and paste the path for our GCC compiler inside here. Now once you do this, you can simply hit the Okay button. And this is how to make windows understand that we have a C compiler and installed. Click Okay. And Okay, and close this window. Now you can go back to Notepad Plus, Plus and write an essay called similarly like void. I will add anything like n, n. That's why the void here. And let's include a library. We will talk about that in the coming lessons. Now, once you are done with this, you should be able to go save your file as a C, fine C. And you can go to the File, select Open containing folder, and simply select CMD. Now you will see the Command Window or not you need to do is simply write GCC, this dot c. And as you can see, the code did compile. Now if you run GCC, as you can see, fatal error, combination terminated. This means that we have the GCC compiler installed. Now if you want to print something, you can simply write print f, hello and save the file. Go back here. Gcc. And once you have compiled the file, you can't seem to write a EXE. And you will see the printed word. As you can see. Hello. Andy will explain these steps in the coming lessons. But this is how to make sure that your compiler is installed. Now, we will use Notepad Plus Plus and GCC compiler, the command window, the cmd to compile our files. And if you face any problem, I'm here to help, please for me. And I'll help you install the software. And the next two or three lessons we will explain different options to write C codes, not just using Notepad blast, blast, but we have other options as well. Thanks for watching this lesson. See you next. 3. Write and Compile C Codes in your browser : Hello and welcome this new lesson in which I'm going to show you the second and easier option to write and compile C codes. Go to animal browsers and lie right online gdb. This is the word online, gdb. Now once you do that, you will see the first result outside called online gdb.com. Click once and you will see a compiler. As you can see, this is the area where you write codes. And from the top right menu here, select the language, simply hit the C language and run. Now once you run this compiler, you can see that word would print f hello world. So it will print hello world down here. So this will be your command window in which you will see results. And this will be the area where you write code stuff. You have any problem in the code. It will indicate that in this window, as you can see, it's a very proficient on online compiler that you can use. Now, what we recommend is that you go and look in using your Gmail account or sign up with your Gmail account or Facebook account or GitHub account, or simply by writing an e-mail and password. I usually prefer going with Google. So we will sign in using Google. Now. Once you sign in using your Gmail account here it's asking me for my security code. So once you are n, similarly write the code. Once you are in, you will see a project's window or tab here. Or you can create a new project. Now if you created a new project, you can easily save the new project to your library and you can go back to that project anytime. So simply hit the save button, name the project distinct. Click Save. Now we have a new project called testing, and you can create more than one file inside the same project. So let's call this test. So now we have a C project with more than one file. Now, once you hit the save button, you can go to My Projects and you can see that testing project that you made. This is a very, let's say, comprehensive platform. It's for free as well. And you can access it from your mobile phone if you don't have a laptop and you want to start coding in C. Now what we will do is we will create a classroom and we will nancy link to this classroom so that you can submit the homeworks for this course. Inside this cluster. As you can see, you must create an account in order to submit the homework, save your projects, and save your work. That's it. Now, once the homework is submitted, will explain to you how to access the homework and how to solve it. Thanks for watching this lesson. If you have any questions about how to create a new project and how to like a C code inside this platform. Feel free to ask this. 4. Download and Install Visual Studio Code To run C programs: Hello and welcome to this new lesson in which are going to show you how to download and install Visual Studio Code and how to enable C and C plus plus programming using the software. So the first step is go to our browser and right visual Studio Code. Now, as you can see, it's basically a software provided by Microsoft. You can simply download for Windows by clicking here. Now, as you can see, this is a quick overview of the software itself. And it's asking you if the download not starting, try this direct link. Now once you click on the direct link, the download will start. As you can see here. I will use another software to download it. Now as you can see, the downloads started. It won't take long. It's about 76 megabytes. So after that, you will have the Visual Studio Code and setup file and we just need to install it. Now, Visual Studio Code is a software used for writing course and other programming languages like C plus plus C-Sharp, Java, Python, PHP, and go. Click Open, click Accept, next, next, next. And if you want to create this icon or add open with code action to the File menu. You can click on this. Then install. And as you can see now, it's extracting the files. Then it will start the installation process. Usually, it doesn't take long. It's a very light software, but it has a lot of capabilities. Now, as you can see, we have the software installed, click launch Visual Studio Code, and hit Finish. Now once you are here, then you are good to go. You can choose the look you want. We can go with the light or the dark. Now, since I'm recording videos, going with the light one is better than going with a dark one or the high contrast one, but most programmers prefer the dark one. Now I will choose the right because it will show you the codes in a more clear way. Now, once you are done, you can also browse color themes. There are other themes as well. Now you can complete this checklist or go to the next section. As you can see, redefine your editing skills. You can open editor playground to change different things. Now, you can also go here to this area and create a new file. As you can see, or open a folder. Now once you have the software installed, then you can go to the next step. The next step is to install the extension C, C plus plus extension. So go here to the extensions on the left side. In the search bar, right? See hex connection. Now as you can see, here, we have the C, C plus plus, saying extension. The first one, and this is the second one. This is the third row. Now we need this one. We don't need this one. Just make sure that you have the one that says CC plus plus Intel. Since debugging and called browsing. Now once you are inside this, you can click the Install and then installation process will start. Now, you need to wait a few seconds for the installation process to finish, because now it will call the extension for Microsoft servers and download it and install it or on your operating system. Now, once you see the uninstall button, it means that we have the extension installed successfully and we are done with this step. Now, the next step is to install the C compiler. We already did that and appear as lessons, so we will do it quickly in this lesson. So go right, men, GW, dash W 64, and go with this link. Now we have more than one. You can choose that minimalists. So manger, WOW, 64 minimalist and click once on the source form here. And you will see the download page. Click the Download button. Make sure that you have this name on your browser. And hit the download. Now it shouldn't take long as it is an online compiler. So here it is. Click once. Now you need to follow my steps as it is click Install. Now once you click Install, you need to choose what do you want to save this file. So let's call it when GW. Or you can add 2020. Whatever you want. I will leave it as this man, GW, and click Continue. Now make sure that you have dislocation, memorized or copy it. Now click Continue. Now let's you seconds for it to call that list of things available on the server. Now click Continue. You will see this list. Here. You can see the list of things available for you to download. We need to download this map for a solution, and we need the GCC, g blasts blasts. Now, make sure that both of these are selected. And once you are done, go to the installation and hit Apply Changes. Now it will ask you if you are sure, click apply. And it will start connecting to the server and downloading and installing all of these components. Now that shouldn't take long. Now once you are done with the download and installation of GCC compiler, you need to go and sit the environmental path. So make sure that you go to the Start Menu and right environment and hit here. Now sometimes these patterns are not enabled by default. So in this case, you need to go to your PC, right-click, select priorities. And from there go the advanced system settings. In here, you can see environment variables. Click once, and you will see this list. Now go to the system variables. Make sure that path is selected. Double-click on it, and you'll see this list. Now all what you need to do is him visiting, click New and paste the URL for diamond UW and make sure to add the pin folders. Now, once you have done, since I already have it here, I will leave this one. I already have it here. As you can see, when you w and w 64 slash pen, you make sure that you are referring to the pin folder or the bin folder, sorry. Now click Okay, and Okay. Now the last step is distinct. So go back to that Visual Studio software, which is this software. And let's start by making a new folder to store our C codes. In order to do this, I will go and add a new folder to the C directory. Let's call it C codes. New Folder. See codes. Double-click. And here it is. This is all for. Now. Once you have this folder and go back to this menu and click Open Folder. Go back here and select the folder. Now once you select the folder, it will ask you if you trust the authors are not select trust. And yes, I trust that authors. Now we are inside of the folder called C codes, and we can start writing our she calls inside. So click here, new file. Let's see. Now inside here we will write the same code that we wrote before. Hash include std. Now int main, void. Now once you are done, simply go here and write print f. Hello testing. Now when you finish. Getting your first C code, simply right-click on this C code and you'll see a list of items. First, you need to make sure that you have already saved your file. Now, as you can see, do you want to install the recommended extension for C? Click Install. It's written on the right side of this window. Now here we have the C, C plus plus extension. As you can see, it's installing a lot of extensions related to C programming, CC plus, plus extension back. But even without the extensions that are now uninstalling since we already installed this extension, you can go to your C file, click run and hit the Start debugging. Now it will ask you if you want to debug using GDB or the Windows select GDP, you want to combine using GCC compiler or another compiler will compile using the GCC compiler. Now as you can see, it's compiling the code. As you can see, exited with code 0. And we have 0 errors. So the code did run correctly. So if we want to run the code without debugging, simply go back and hit run without debugging, and it will simply run the code without debugging the errors. Now if you want to make sure that the program did run correctly, you will see added EXE file beside the main file. And this is the executable file that you can run. And we'll show you a command window. Now, right-click on it, orbit real and File Explorer, and double-click. It will show you a command window, but it will quickly disappear. Now if you want it to stay, you need to add a scan f sentence. Now, save the code and run the code. Now once you have done or the running the code, you can go again and open up the text, color taste that EXE file. And you will see the hello testing world wishes this work. That's it. This is how to enable debugging on Visual Studio Code. We won't use this software. We will use the Notepad Plus, Plus, but this is something for you to know. Now some people might want to see the output and this window, like when they are running that C code, they need to see the output inside this output window, not inside that EXE file that we just launched. And to do this, we first need to do the following. You need to go to the tasks, the JSON file, which is basically just as fine. And here you will see the label line GCC, that EXE build active file. Now, this is the written thing inside your label. You need to go back to the JSON file, which is this file. And you just need to add the external console here, change it to true. Save, and now hit done. As you can see, now you can see the output results for your pod hello testing. Now it did run the output directly after running our code. And this is one of the easiest way to implement this. If you have any other questions I'm here to help. Thanks for watching this lesson. See you next. 5. Write Your First C Code and Compile it: What is C programming? In this new lesson, we'll talk about a C program, the basic structure of a C program. And what is a C program has made to form C is structured programming. It means that the C program is composed of small parts. We call function. And you will hear the word function a lot while you are programming in C. The first function to be executed, which is the entry point of the program, is called main, which is the main function. Some functions may be a standalone file for organizing. These are called Library. Now the basic structure of a C program is basically the main function. Now this main function can be or can include one or two functions. As you can see, function one and function two. Now, the C program that has more than one function. These functions can be composed and stored inside a library. And we will create our own libraries at the end of this course. What I need you to understand at this point is that your C program, we have a function call, the main function. This is the first function to be executed in our program. Now, this might be vague for some people, but we will see it in action in the next lesson. Now, library is basically a collection of functions that do specific thing. Like you can have a library that print things on your display. You can have another library that has functions that help you read data from the user. This can go on and on. So a function is a piece of code that does a specific thing. The main function, the first function to be executed in our program by the compiler. The library is a collection of function that does a specific thing and that you can easily use inside your code. Now, let's take a quick look at our symbol C code. As you can see, this is the first score that you will see in our course. The first thing up here is called a multi-line comment. Now this multi-line comment means that this is not code. This is something you usually write for yourself. Like to remember what is this course is all about. Now, to write a multi-line comment, you need to make sure that you have that backslash and allosteric. Now in this area, as you can see, we have a backslash and Asterix, and you must end it with an asterisk backslash. This is the beginning, the beginning, and the end of a multi-line comment. Now, another thing written between these two signs is called a comments. So this is not a code and won't be executed as a code. This is only for you to see. Now, the second thing here is that include command. Now, when you want to include any file, any library, or anything inside your C program, you must use hash include. This is called hashtag include. Now usually it is followed with these signs and the name of the thing that we want to include. Here we are including a file called stdio.h and we don't use we don't want you to understand at this point, what's the meaning of this file? All what you need to do is that when you want to include a library or a file, you must use the hash include hashtag, include the name of the file between these two signs. We also have something called a single-line comment. Now, we already mentioned the multiline command up here, this area. But what you want to make only one line comment, not multiple, multi-line comment. You can easily add two back slashes here. And these two slashes will make this line a one-line comment. So anything that you like and this line will be considered as a comment and it won't be executed. Now, we already mentioned that your program must have a main function. The main function, basically the function that will be executed first and our program. As you can see, this is the function name. Now, void and void are two words that have meaning, but we will not explain them at this point. You just need to know that you must add two parentheses at the word void between them. And leave a space here and add the word void before the name of the function. Now, this is a curly brace. This is the opening and the closing of the curly brace. Here, we added another multi-line comments. Call the main function and parse string to it. Now, this is the main function. And inside here we are writing our very first C code. This is a print f, and from its name, it's basically for printing text onscreen. And as you can see here, we are printing this text Hello World. Now you must add two parentheses and two, as you can see here. Quotation marks. Now, these two quotation marks, we'll include that text that we want to print in here. Again, this is how to write your very first C code. Now, anything that you write inside that print f, two quotation marks will be printed on screen. And to make things more clear, Let's write this code and try to execute it as our very first C code. Now we already mentioned that we will be using a website called online gdb for some of our exercises. Since this is the first exercise, we will use it, but you are free to use the Notepad Plus Plus as well. Now, we already mentioned that in order to write multi-line comment, you need to add these two signs and close them with these two signs. Now let's slide. This is our first C program. This thing. And now these two lines are basically a comment. It's a multi-line comment. Now, let's add a single line format. This is a single line comment. Great. Now let's start by including the library. So we will include that std IO, or standard input output library to allow us to print on screen. So right, include the larger, less than sign and the library name. That's it. Now, this means that we are asking the compiler to include the functions inside this file inside our C program. Now, let's apply our main function. Usually the best way to write things is by writing the syntax, then writing the code inside of it. I like to ride the syntax in one line. As you can see, void leave a space and the right main, which is the name of the function. Then add two parentheses. This one, this one, add the word void between them, and add two curly braces. Once you have this, simply, put your mouse here. Press Enter what your mouse between the two curly braces and press Enter. This means that we are good to go. Now, let's print something. What we need to print here is this is our first C code. Now, you need to choose the language from the top right corner. Select C and hit the Run button. As you can see, this is our console window. This is our first C code and it's working properly. Now if you did reach this point and you managed to write this, and you saw this output means that everything went well for you. Now, you can copy the whole code. Go to the Notepad Plus, Plus. Here. Create a new file and paste your code. Make sure to choose the C language as your default language. And save yours. Leave it has new. Now, go to the file. If you've already followed our installation video, the download and install software section, you should be able to use not by the blast, blast for compiling your code. So click cmd. And once you see this window, you need to write GCC. After that, you need to write the name of the file New three. Let's see. Now, this means that we are asking the compiler to compile our C code, which is the first step. Let's say playing or making sure that our code doesn't have any orders. Now if you combine the code and you didn't see anything, it means that everything went well. Now your documents folder, we'll have a new file called a ducky XP, which is basically the file that has the output of this C cold press Enter, and you will see the very same code. This is our first see cold. Now let's review the steps of GCC, which is the compiler, that filename. Then a dot EXE. And you should see the output. If you saw the output means that everything went well for you. Now if you compare this output with the output from before, you can see that they are identical. The same sentence here is rated and our CMD or command line window. That's it. This is the end of our first line. 6. How to search for solutions as a Programmer: Hello and welcome this new lesson in which are known to explain how to search for a specific thing and C. Now let's say you were writing a C code or you run into one of our quizzes or assignments, and you didn't know what to do, or you didn't recognize a function, line of code or anything. This happens as we add assignments and quizzes, we try to diversity. So you might find a quiz question that is not explained in the previous lesson. And we need you to search for a solution. This is to make sure that you can search for things that we didn't say xy plane and our lessons. And to make sure that you have this, let's say talent. We call it a programmer search talent. Now, go to Google. The first thing that we need to do is to make sure that you are writing your search term or your search term, right way. Let's say that we want to search for a specific function. It's called get Nc. Now you need to make sure that you are writing C without PSI-BLAST are solid C programming. You must write C programming to make sure that you don't get results for C sharp or C plus plus because they are C but with different approach. So as you can see, see Get function, this is the first result. And this is the explanation that gets function enables the user to enter some character followed by the enter key. All the characters entered by the user gets stored in a character array. Then I'll characters added to the array to make it as trained by default. Now, gets allow the user to enter the space for it. It's thinks this is the whole explanation. This has everything you need. Now how to use it? You can go to the first result. Now, as you can see here is that declaration gets and this is how to use it. You must first make an array, then use the gets function. These things would be explained during the lessons are raised and these things, but this is how to get adult. Now, other places to look for the results are tutorials, point Tutorials, gateway, gigs for mix. These are very great websites and you can go and write Stack Overflow. This will make sure that you will get results from Stack Overflow, which is like programmers, google. Programmers go to StackOverflow to write down their problems so that other programmers can help them. As you can see, you can check more than one result. And let's take the first result. Here you can see that there are a lot of sea problems posted by a lot of people. You can get. And see. Now, it's asking for whomever vacation. As you can see, these are some of the results. So whenever you have a question, you can ask it and a lot of Q and the board will be sure to help you that question. If you found something I loved the quizzes or the multiple choice questions that we didn't yet exit plane or you didn't recognize. You can ask in the Q&A board so that we can explain it for you or give you proper information about it. Again, will sometimes add few questions to these assignments and quizzes to make sure that you can look for answers yourself. Then come back to solve the quiz and assignment. This is something if the programmer must do to be able to do great projects in the future. That's watching this lesson. This is. 7. Comments in C: Hello and welcome to this new lesson in which we are going to talk about comments. Comments and C are basically on an executable text used to provide documentation for the code. It provides clarity to the C source code, allowing others to better understand what the code was intended to accomplish. It is always recommended to use comments in your code. We already mentioned that we have two types of comments, that single-line comment and a multi-line comment. The single-line comment is basically any line preceded by two forward slashes. As you can see, the forward slash is the sign that you can easily derive using your keyboard. And this is the final shape, two forward slashes. And this is your comment. While the multi-line comment is any text starts with a forward slash followed by allosteric, and ends with an Aztec followed by a forward slash. And this is how it looks for slash asterisk and then forward slash. This is the multi-line comment. Now, we already showed you how to derive these commands, but let's refresh our memory. Now as you can see, this is the forward slash followed by an asterisk. And this is an asterisk followed by four slash. Now phew close this. You can see that these two commands are together. These two forward slashes followed by one line, which is the one-line comment. Now, another piece of information that we can mention is that when you write two forward slashes anywhere, even inside the main function, they will be treated as performance. Now if we want to commend this line, print f, we simply add two forward slashes, as you can see here. Now, these two forward slashes would mean that this sentence won't be executed. So let's save this file. Let's open it. Using CMD. We need to use the same name, gcc 1, first C code. But c does. You can see because our filename has all of these spaces, it won't be compiled correctly. So in order to compile a C code, then m must include no spaces. And this is a very important note. Now, save your file again and remove less spaces. Now, let's do this one more time. Let's file, go to File open CMD and write gcc by the filename 1, first C. C. Now as you can see, we didn't leave space. Okay, let's leave this space. Now. The code compiled correctly, if we try to run that EXE, nothing will be printed because we commented the line called print f. This is our first C called. Now if you remove that and let's save the file again by clicking here and went back to this command window. We can run the command again and we can use the a dot EXE. See our output, this is our first C code, as you can see in here. This is how you can use multi-line comments are single-line comments, and this is how you can use them in debugging as well. So if you suspect that this line is causing a problem, you can simply commented using single-line comment with two forward slashes or double line command, using the forward slash and asterisk, then the asterisk forward slash. That's it. Thanks. Flushing. This is Ashraf. 8. Strings and Escape characters in C: Hello and welcome to this new lesson, interatrial going to talk about a very important topic. And C, strings, NC sinks and C are basically a way for you to explain or type things. It is compromised of a set of characters that can also contain spaces or special characters and numbers. Now, in C, string is represented between double quotation, like these two double quotations, as you can see in this image. This is astray, or this is simply anything that you write between these two double quotations will be considered as a string. Print f function, the function that we already used twice. We'll print the string passed to it, as it is. It's called string literal. Now, escape operators may be used inside the string, like the backslash, as you can see in here, with a letter following the backslash. This operator means Here's tab, newline or codes. As you can see, if you use this one, it means that this sign, please add a new line. If you use this one, means add a horizontal tab after this location. If we use this slash v, means that we need to add a vertical tab inside our swing. If we need to show the single quotation or double quotation inside our string. Once we print it, we can use the slash single quotation or double quotation from double-quotes. Now, things might be more clear when we execute them. So let's write this out. Let's pull fluids. As usual, the std IO library and write the main function. The same way we mentioned before. Press Enter here and press Enter here and write your code here. So print f here. Between the double quotation, we will add our string. This is our string. Now, if you want to print a string and add a new line, this is that second line. Now without adding the slash n, this text will be printed like this. Let's add a semicolon. As you can see, this is out string and this is the second line. Now they were printed on the same line. We want to add a new line. At the end of the first line, you can add a slash n and run again. Now as you can see, this is the first text and this is the second text, and we added a new line here. Now let's say that we want to print a single quote or double quote. If you added a single quote here. And try to run that code. As you can see, it can directly be printed. Now in some compilers, this will not print directly to cause an error. So you need to add a slash and then run the code. As you can see, this printed as well. Now, what if you want to add the double quote? You can add the double quote here. But if you try to run the code, it will show you an error. As you can see. Now this own scores because we know that the string is something we wrote between two double quotation. And since we added a quotation here, it is. Considering that string that we want to print is this thing. And it's not recognizing this part of the string because it's not included in the first double quotation area. To make sure that this won't cause a problem, we can simply add a slash. Now when we run the code, it will print the double quotation or double quote. Now that single code is printed, the double quote is also printed. If you want to add a space or a tab space between these two works, we can simply add slash t. Then run. As you can see, slashed, he added a horizontal space between these two words. Now this space can be either four or eight depending on the compiler. Now, we also mentioned the vertical spacing. If you want to add the vertical spacing, spacing. Here we add level horizontal spacing. Simply add slash v. And we'll add a vertical space between this part of the text and this part. Now, click Run, and you'll see that this is printed on the first line, and second line is printed here. So we added one vertical space between these two lines. These things that we wrote here, here, here, and here, and here are called escape characters. Now, skip characters are written using the backslash, not a forward slash. As you can see the commend, the singular comment is written using the forward slash, but the escape character are written using the backslash. So it can be slash t slash v slash single quotes or double quotes slash n. These are the one that we introduced in this lesson. Slash t will add a horizontal spacing. Slash v will add vertical spacing as we saw here. Slash single quote will add the single quote or on printed on the text slash double code will print a double quote on our text. Slash n will add a new line, as we saw here. We added slash N here, and it inserts the new line. So these texts are not like printed on the same line. These, this is how you deal with this thing. Now, to print saying we already mentioned that you can use the print f function and this is a good piece of information that we need to mention here. Print f function takes two, as you can see, parentheses. And inside the two parentheses you must bring to double quotation or double quotation, sorry, and end it with a semicolon. This is the syntax for print F. Now print f function is a function defined inside this file. It's called standard input output, the texts, or the header file. And we'll talk about it, a file in more details in the coming sections. But what you need to understand is that without including this header file, our main function won't recognize the print f function that is used to plain text. Print here means printing. F here means format, means format. Now, this is the string literal. So print format, we'll print the text or the string as it is, as we saw here. And output window. That's it. Thanks for watching this lesson. If you have any questions, please ask Kentuckian the board. This is Ashraf. 9. Variables in C: Hello and welcome this annulus one in which are going to talk about variables in C. Variables. And C is basically a place that holds a piece of data. So we all know that memory inside our computers or in embedded systems, microcontrollers will hold variables. Now, we won't go into the tails how memory process variables. But all what you need to do is that a variable is something that holds a piece of data. It's typed values in data and size that needs to be saved. In most, let's say, Use Cases and embedded systems. We have limited data types. These primitive data types are plotting types, as you can see in here. These ones types. The floating types is the float and double. While the decimal types are the character and the interior. Now, the floating types will hold information that has a float like 3.21.4. And these things, normally the flaw size is four bytes. And this is a very good piece of information if you want to keep track of your memory, especially in embedded systems. While double all the same type of information that afloat holes. But the size is doubled eight bytes. That's why they are called floating types. This human tribes, other hand, are the character and integer. Integer is the most common used data type. In C, It's about one byte in size, while the character is about eight bytes in size. Character is usually used to store characters like a, b, and c, while integer is usually used to store numbers. Float is used to store numbers with a floating point like 3.2, envoy to these things. And these are the most commonly used data types in C. We call them primitive data types. You can split them into floating types and decimal types. Floating types are float and double. One. Decimal types are characters and integer. We use them to store information like username or password. All the calculation results. You need to take along that datatypes may vary from each compiler to another. So in one compiler, an integer can take one bite. In another compiler, an integer can take four bytes. Now, the next thing that we need to mention is the syntax. How do we define variables in C? To define a variable, you need to follow a specific syntax. First, you need to write the datatype, which is the first piece of information in the line. The data type is character, integer, float, or double, depending on, depending on what type of data you want to store inside it. Then you must leave a space. After the datatype. After that, you can write the name of your variable. Here, the variable name is X, Y, and Z. Now the next step is defining or choosing whether you want to add an initial value or not. Now if you want to add an initial value to a variable, you can simply add the equals sign and add the value. You must end the line with a semicolon. Like every line in C must end with a semicolon. Now in the first line we define char and initialize it with the value nine. While in the second line, we initialize an integer named it y. And the initialization wasn't done. In this case, it will have a random value. We call it a garbage value. This is not a use case that we would love to happen. So usually we initialize all of our variables. Here. We are defining a float and initialize it with a floating number like 6.52. Again, we prefer to initialize all of our variables to an initial value of 0. Let's say if you don't have a specific value in mind, but don't leave it uninitialized. Otherwise you will end up with a garbage value. Now, let's see what will happen inside our memory when we initialize a variable. Now let's say that this is our memory. Now inside this memory, we have different areas, places. And we initialize a variable called x with the initial value of five. Now what the compiler will do is we'll go to the RAM or memory. It will name this location x, and we'll give you an initial value of five. When you initialize another variable, we call it y. Without adding a value, it will go to this location, or this memory will say, this is y, and it won't give it any value. Now, whatever the previous value that was here might be as it might be assigned by default to this variable. And we usually call it a garbage value. Now since integers takes only one byte, I gave it one byte. So this is one byte of memory. But let's say that we want to define a character M. And let's give it a, let's not give it a value. Now when we go to memory and want to define m, It will take this byte and this one. And this one. And this one. So depending on how many bytes the character will take, which is eight bytes, it will take eight locations. So it will take also the dislocation, dislocation 12345678. So it will take all of these locations because it tastes eight bytes, while integer takes only one byte. And this one takes only one byte. So why is one byte and x is one byte? So in total, these three variables stock one byte of memory plus one byte of memory, plus eight bytes of memory. In total. They took ten bytes. This is a very good piece of information, especially when you are dealing with systems that have low memory size. Like an embedded systems. It ten bytes for three variables. Again, if we haven't defined anything here, like we haven't said, equal five or something. We just ended with a semicolon. This will be a variable that we didn't initialize. So it will take garbage values. We call them garbage values because these values are values that we haven't said. And it might be a previous value from previous variable declaration in memory from any other software. Now, let's test this out by going to the Notepad Plus, Plus and typing some variables. Now as usual, hash include that std, IO, the edge, and write void, main. Void. Between the two curly braces, we'll start typing all variables. Let's change the language to c. And x equals 0 into y equal ten. Hello, The equals 10.5 and double c equals 4.555. These are the different types of variables. These are initialized variables. And this is an uninitialized variable, has garbage value. Now some compilers say or define the garbage value as 0. Otherwise leave it like to be a random value from memory. But the better use case or the bizarre programming practice is to define this to 0. This equals 0. And we already mentioned that we need to add the datatype, leave a space and the variable name, add the equals sign and the value, and in the line with a semicolon. That's it for this lesson. Thanks for watching. This is Ashraf. 10. Rules in naming variable in C : Hello and welcome to this new lesson notes you are going to cover some rules and naming variables. Now, the first rule is that a variable may contain the following. May contain underscore, may contain a number between 09. It may contain capital letters from a to Z and small letters from a to Z. The first character of a variable should contain an alphabet or an underscore symbol. So the variable name cannot start with a number. For example, it can be integer A4 for integer for a. Now, a is the wrong one. Let's mark this. As you can see, an A4 started with a letter, while in for a started with animal. So a variable name cannot start with animals, as we already mentioned, can start with either a letter or underscore. So this is the wrong one. Now, blanks and columns are not allowed. And blanks is basically when you add two words and you leave a space between them. Commas are also not allowed. And we are going to see these in action in a few seconds. Variable names should not be reversed or served work. Now reserved word is basically a word that is reserved for our compiler, like print f for example, or end. So there is no way that you can name a variable n because n is already reserved for our compiler as an integer. So blanks, commas, and special symbols are not allowed with the underscore as the only exception. So any special symbol is not allowed except for the underscore. Example, the add sign that asterix that dole out of the blast and many more signs are not allowed. A variable name cannot be repeated in the same scope. So if you have named a variable x, you cannot create a new variable and limit x as well. The variable name must not be reserved word, as we mentioned earlier. Now, let's see these things in action. Now as you can see here we are inside the notepad. You cannot name a variable or with other served or like int. N is basically the integer data type and you cannot name it float. All of these words are reserved for the compiler. You also cannot name a variable starting with a number. This will give you a compile error. You can name it A9, starting with an alphabet, and it will work just fine. You mentioned that you can add special characters like this and this and this to the variable name. However, if you want to add a special character, you are allowed to add the underscore sign. This is the only thing that is allowed in the variable naming. You can even add underscore sign at the beginning. So our variable name can start with underscore or with a letter, but it cannot start with a number. You cannot use the reserved words, as we already mentioned, like integers. And you cannot name a variable or use the same variable name twice, like int x, x, it will give you a compilation error because here you are defining a new variable, naming it x. And you are telling the compiler to go to the memory and assign a location with the name x as an integer. Then you are, you are telling the compiler to go again and assign that location with an x and the type of integer. And there's already a variable named x. So this will give you a compilation error. You cannot use the same name more than once. Now the last thing that we need to mention is that you cannot leave a space or a blank in the variable name. Let's name it new variable. Now this will give you a compilation error because n, nu is the variable blank and the other word or something else. So the compiler is not recognizing them. If you want to leave a space, you can either use the underscore or you can use a naming convention called camelCase, where you name the first letter of every word with a capital letter. So new variable, name like this, or simply use the underscore. Underscore. And here is another underscore. Now, this is another solution. You cannot use commas inside the variable name. As already mentioned. You cannot use blanks and you cannot use reserved words. You can use special characters set for that underscore sign. And you cannot use the very same name for different variables of the same variable in the same scope. Now when we say scope, we mean these two curly braces. This is the scope of these variables. Now if I tried to call x outside the scope like here, it won't recognize it, but this is something that we will talk about later. So let's summarize. A variable name may contain underscore numbers from 0 to nine alphabets and capital and small letters. The first character of a variable must contain either on alphabet or an underscore sign. It cannot start with a number. Blanks and commas are not allowed. Variable names should not be reserved word. And plus the fact that special characters are not allowed except for the underscore. Thanks for watching this lesson. This is optional. 11. Printing Variables with Printf in C: Hello and welcome to this new lesson n, which are going to talk about print function. Now, look at this code. Let's discuss what's happening inside this code. First, we are calling the library. Then we are defining our main function as we usually do. Then we are defining an integer valuable variable named x and y are giving it a value. Often. This is a semicolon to indicate that this is the end of this line. We are calling the print function. And inside it we have written the variable value is We ended the line with a semicolon. What is the expected output of this program? Now, pause the video and try to guess the expected output. I'll give you five seconds. Hopefully, you will pause the video and try to figure out the output without running the code. Now if your answer was this, the output on the display will be the variable value is X. Then you are right. This is a string literal, so it will print the string as it is. It won't print the value of them, won't replace x with them. Here. This is what this lesson is about. Now, the print function flashes the variable inside this thing. The print function can print a variable inside the string. It could be done by inserting something we call format specifier. The format specifier is basically something you add inside the string that indicates that you want to print something. The format specifier will be replaced by the value specified in subsequent additional arguments. Inside the format specifier to be replaced by the specified value after the additional arguments. If things are not yet clear. Let's first talk about the format specifier syntax. Most common specifier used for print function, our percentage f, person C, and person D. Percentage f inside the string indicates that you want to replace this with a floating value. While format specifier or percentage c, means that you want to replace this with a character value. The last one is the most common one of these three is the percentage d. It indicates that you want to replace this format specifier. The string with a decimal value, usually follows this pattern. The variable value is. Then you add the format specifier between the double quotation. Inside that x is. Now the new thing is that you must add a comma and the variable name. What this print function or this line will do. It will replace the format specifier, which is percentage d, with the variable value of x. So it will print the variable value is ten. And this is called a format specifier. You need to memorize this world, as we will mention it a lot. Now, let's see this in action. Now, let's write, as usual, includes STD or the head of void main void as usual. And try to write the code from scratch every time so that you are getting used to writing C calls. Now, let's define a variable. A variable, give it a value of ten. So we define an integer value, an integer variable. The name of the variable will be x, the value or the initial value will be ten. Now let's print f. The variable. The x variable value is here. We need to add the format specifier. I added percentage d, because integer is a decimal value. If it is a floating point value, we need to add f. If it is a character value, we need to add C, D here. Then add the new thing, which is the comma and the variable name x. Now this line will print the x variable value is replaced this with ten, which is the value of this variable. Let's save our work. Let's call it three variable. And let's try to run it. Here we have the compiler GCC, three random variable C and E. As you can see, the x-variable value is, the x variable value is. And that percentage d, which is the format specifier, was replaced with, then. That's it. This is how easy it is to print a variable within the print f function. Now let's talk about common mistakes. Most people write x here instead of writing the common value, which is all the format specifier. And when they combine, this is what they see. The x variable value is x. So we need to replace this with d. Now the format specifier or be replaced with the X value. Another thing that you can do is to blend more than one variable on the same print F function. If we want to print y, you can add that value. Let's print it on a new line. So add percentage n, which is the escape character that we already introduced. The value of y is add another format specifier, percentage d, and add another comma, then y. Now what will happen here is assembled. It will replace the first format specifier with x and the second format specifier with Y. Now you have another variable. You can add another format specifier and it will be replaced with the field variable, and so on. This string will be printed as it is. Now. Only thing that will be changed is the format specifier. The first one will be replaced with x, the second one will be replaced with y. Let's save and compile the code one more time. Now I want to clear that CMD or the command window simply lights CLS, or clear screen and will clear everything. Now let's compile it. Gcc and C file name. Then run. As you can see, the x-variable value ten, which is this line. And then slash n means that go to a new line. The value of y is, instead of percentage d, we will see the value of y, which is 15, as you can see, 1015. Now, what I need from you to make sure that you did understand everything that we've learned in this lesson is dried this very same code. And make sure that you are looking to the same results on your screen. Make sure that you don't add the closing of double quotation here. Because in this case, it means that you are printing this. Now let's see what will happen if we did that. Let's clear our screen. Run the file. As you can see, the x-variable value is a very huge number, and the value of Y is a very huge number. Now, this is the default value for decimal variables. And this compiler, as you can see, now, it did print x and y as a normal text. It didn't replace any of these things because we misplaced the double quotation. So you need to remove it from here, add it to the end of your text. Make sure that you have the commas right place and the variable names. That's it for this lesson. Thanks for watching. This is optional. 12. Reading Input from User in C: Hello and welcome to this new lesson in which we are going to talk about scan f or scanning a value from the user. Now what we covered so far is how to print a value on the console window. But what if we want to read the value from the user? This is where scan f is use. The scalar function is used to get value from a user and save it to a variable. It is a part of the std IO library, the library that we include at the beginning of our code. Now, the syntax for this function is simple. You just tried scan f. Then you open two parentheses. Now, first part is the format specifier. Here you must add a format specifier between two double quotation. Let's say that we want to read an integer value. So we'll add percentage d between these two double quotation. Now, the second part is adding a comma. Then the add sign. After the add sign, we need to add the variable name. So in this case, let's say x, right? And x. Now, this is an example. As you can see. Here, we defined a variable, we call it x, integer x. And then we use scan f with these two parts. The first part is the format specifier, then a comma, then the add sign, then the variable name. You need to make sure that you follow the very same structure. Like in this line. Scan f, percentage d, which is the former swift file between two double quotation, Acoma, then the and sign and the variable name. Then close the parentheses and add a semicolon. Scanf function, again is a part of the studio or standard input output function. So there is no need to add any or include any other file. Now let's see this function in action. Now let's do the regular thing. Let's include the function that had the libraries or print f and scan. Then let's add a main function. Now press Enter here, press Enter here, change the language to see. Now, let's define a new variable and give it an initial value of 0. Now print something for the user to inform him that we want him to enter a value. Enter your age. And let's change this with h. Now, this will print this sentence on the console window. Informing values are that we want him to enter his age. After that we will use the scan f function. Now, the first part is the double quotation that coma and the, and sign. And the second part. Now between these two double quotation, depending on the variable type, you must add a format specifier. Here it would be percentage d. Now, if this is a character which will be percentage c, If it is afloat, to be percentage f, as we already mentioned. So we'll add percentage d. And here we will add the add function or the and sign, sorry, the variable name, age. Now this will take anything that they use are right up to the point that he enters. Enter. Which means that he finished entering the text. And we'll store it inside a variable called age. Now, this line will read the input from the user. So let's add another line to plan the age. Let's write print def. You age. And as we already mentioned the previous lesson to print a variable, we must add the format specifier inside the two double quotation. Then add a comma after the W creation and the variable as it is. Now, to make sure that we see all of these, each one line or a new line, we need to add a slash, slash n. And here are the slash n at the end of each line. Now, once you are done, click Save, and let's call it scan variable. Now, let's go to file as usual, open then CMD. Now in here, right, gcc, c. We are done. Let's zoom in to see. Now write a good EXE, which is the executable for our C file after compiling. So as you can see, integer h, Let's compare to what we have here. This is the first print f function, enter your age. Now after this line, as you can see, this is a blinking cursor. For the scanner. I would write 32. Then I'll press Enter. Once I press enter, it will execute the third line. To write your age is the age value here. So please enter. Your age is 32. That's it. This is how easy it is to scan a value from the user, store it in a variable and print it and a new line using print f. Now if you have any questions about this, please ask. In the Q&A board, I'll be more than happy to help. But as you can see, it's a very simple thing to do. Thanks for watching this lesson. This is Ashraf. 13. Arithmetic Operators in C: Hello and welcome this and you will have some charcoal talk about operators. Operators are very important thing when you are programming because you'll need them when you are doing calculations, when you are checking if a condition is true or not, or when you are inside the loop and you want to increase a value. We have different types of operators and in this section, we will explain them one by one with an example. And we will try to make sure that you understand each and every one of them with I use case and a scenario. The first one is that it's not a cooperation. Now, cooperators, there are two types of them, uni and Pi, and we'll explain them in a minute. There is also the width wise operators which are used to play with pitch level. The assignment operators, relational operators, logical operators, and other operators like the size of operator, the ternary operator, the address operator, the difference operator, and that subscript operator. These are only the names. So let's get started with the arithmetic operators. Now this is a table that has all of that. It's not a cooperators. Most of them are straightforward. First thing that we need to explain is the world. By. Now, there is the union and the by. The by is basically operators that takes two operands. So they must have two operands to be called by. An example of this is that summation, which is basically this side, and a subtraction, which is basically this sign multiplication, which is the asterisk sign division, which is the slash sign modulus, which is the percentage sign. Now let's talk about each of them. The summation is basically used to some two operands. This is the first operand, and this is the second overland. Now here we have x equals ten and y equals five. So x plus y is basically a summation operation because we are using that cooperator, the blast. So the result will be stored of the sun, will be stored inside this variable. So x plus y, then plus 15. So ten plus five, sorry, it will be 15. And this is the result. So some variable will include the value of the summation, which is x plus y. Now regarding the subtraction, as you can see, the same example as above, two operands, x minus y, which is ten minus five. The final result is five. So five will be stored inside the sub. As you can see here, sub d equals ten. Now in this case, subs wrong because ten minus five is only five. Now, let's move on to the multiplication. X multiplied by y. X here is ten. Why here is five? Now when you multiply ten by five, it will be 50. So here we have this answer, 50. So the van, the variable called multiply two will be 50, which is an integer. Now, we also have the division X, which is thin by five, which is basically an integer, ten divided by five equals two. So the result will be stored inside the division variable, which is basically two. Now we have the mod psi naught sine is basically assign, that gives you the remainder of a division. So if you are dividing x mod y, now, I need to concentrate on this one. When we say x mod y first, you need to make sure that you have x divided by y. So if x is ten divided by y, which is 510 divided by five equals two, there is no reminder in this division. So the result or the final result for the percentage, which is the reminder, will be 0. Now, if y is divided by x, now, this is a reminder sign. Again. You need to do it first as a deficient, then you take the remainder of that division as the result of the MOD. So y divided by x. Y here is five divided by x, which is ten. Now, when we divide five by ten, this is called a division. So five by ten here, phi one f2. So the final result will be one divided by two, which is basically 0 or five. So in this case, the final result will be 0 and the remainder of this will be five. So that division value will be 0 and the remainder value will be five. That's why you see the results here as it is here. As you can see, odd equals five. Now to make things more clear, Let's try this example. Ten mod 310 divided by three equals three. Now if you multiply three by three, which would equal ten. So ten minus nine will equal nine. Sodium ten minus nine equals one. And this will be the result of the reminders. Let's try this again with this. Now, line. Divided by one equals nine. No fractions, no reminders. So the mode will equal 0, just like in this example at the beginning here. Now, let's try this one. This is the mode division. So 17 divided by 917 by nine. It will equal one. So here, right, one. Now one multiplied by line equals line 17 minus nine. The reminder will be eight. This is the reminder and this is the division. And as you can see here, equals eight. Now what you need to understand is that division gives you a value without a fraction, a fraction to be printed when you are using the division sign, it will just print that value and it will leave any fraction. So in this case, if you need the fractions or if you need a reminder, you must use the reminder Sine. Let's try this in action and let's print the values to make sure that everything we said here is correct. Now let's start by including the std, i, o the texts library. Void, main void as usual. Now let's change the language to see. And I need you to do this from scratch every single time. Now let's solve the value five arithmetic operators. Now, let's define two values, and x equals and y equals five. Now let's do some operations and sum equals x plus y. This blend some equal to b. Let's add a slash n. Here. We can add some. To see the results. Now I'll do all of the operations. So let's do that. Division as well. The multiplication that holds. All of these are pi operators because they take two operands, as you can see here. This is the second orbital and this is the first overland. Now to print the results. Print f equals to d slash n. And here, you can copy this line and paste it here with this slide and paste it here with some modification. Mode, also, just to save some time. Now here it is. This will sum these two operands. So we'll divide them. This will multiply them and this will give us the modes. Now, let's hide the results here. Now first the summation results would be 15. Divisions, results will be two multiplications and will be 50. And the result will be 0, because we already know that x divided by y, ten divided by five equals two. And we don't have any fractions. As we already mentioned, the mode will be or the reminder will be 0. Let's save the work and the code again. Now, let's go GCC. Let's add the filename five. Now here's the filename, as you can see, GCC. To compile it now we have the executable, so like a, E, E. And here we have the result, this 152 for the division, 50 for the multiplication 0 for. Now, to make things look more like, interesting, let's say, let's move this. Now, let's play with the print f function. Let's change this with her son through D plus person to D equals. That is up. Now what I need to do here is to add the x value, the y value, and the results. So to replace this with x first, we need to add x here, as we already mentioned in that print f. Last one. To replace this with why we need to replace y, x. And to replace this with the summation, we need to place the summation. So this will print x plus y equals the result. X will be replaced with the value of x. Y will be replaced with the value of y. This will be replaced with the sum value. The first variable, second variable, a third variable. And this was explained in the printing or printing variables lesson. Let's do the same for all of these. Now we just need to change the sign here. This will be the division. This would be the asterisk sign, and this will be the demand of sine or the percentage sign on to slash n sets. Now, let's go back to compile the code one more time. Clear the screen using CLS and from compiling command, and then run the file. Okay, now as you can see here, we have the first one in the right order, the second, third, 1, the fourth one. There are problem with these because as you can see here, we didn't add the x and y before the div. As we already mentioned, each of these format specifiers will be replaced with associated variable. So save it one more time. Here it is. Ten plus five equals 1510 divided by five equals to ten multiplied by five equals 50. Then the last one. Okay? We have a missing D here. Now, this is a very nice piece of information. As you can see here, we have percent d and we have four centers. And we have their centers me. Yet, it wasn't printed correctly. That's because we have a percentage here inside our string. Now this percentage will be treated differently because we usually use it to add a format specifier. So if you want to print person to sign and our final print f, When do we need to add double percentage like that? Now once you add them like that, the print f function will understand that you want to show the percentage sign ones on the screen. And this is a very good tip. Now going back, let's combine the codes. Entity x e. Now, as you can see, it was printed correctly. Otherwise I won't be printed correctly. So you need to take an oath that you must add double percentage, sign to print it on your console window. So ten minus five equals 0. And these are the main arithmetic operators. That's it for this lesson. If you have any questions regarding anything, I'm here to help. 14. Uni Arithmetic Operators in C: Hello and welcome to this new lesson in offshore. Don't talk about the uni operators. Now in the previous lesson, we covered that by operators. And here we are talking about arithmetic operators. Now, the evaporators takes only one operand, so there is no need for two operands like x and y. One variable will do the job. Now in our case, we have two types of opera. Now. We have the increment operator and the decrement operator. And we have them separated because using the increment and decrement with one variable without the equal sign is something. And using them with an equal sign is another thing. So the increment means to blast signs. The decrement means two minus signs. Now this means add one to the variable. This means subtract one from the variable. Now, in this case, we call this a postfix and we call this a prefix. This is pre, because we are adding the two plus signs before the variable. This is a postfix because we are adding the two plus sign after the variable. Now, if we executed both of these sentences taking into consideration that the variable x equals ten, this, and this will add one to the variable. So x will equal 11. And then here, x will also equal 11 without its post-fix or prefix. Now, when it comes to the decrement, it's basically the same thing. We have a postfix and prefix. This is the postfix and this is the prefix. When we are calling it, knowing that the x value equals ten, it will result in this x will equal nine because the decrement will subtract one from the variable. And in this case, it will also equal nine without is postfix or prefix. Now up to this point, there are no problems. Everything is clear, everything is easy. This will increase the variable value by one, and this will decrease the variable value by one. Now, the problem comes when we have an equal sign. This means that we need to execute this store the result inside the variable. And in this case, the postfix and prefix that we mentioned up here has a different meaning. So let's start with the first one. This one is our postfix. This is basically a sentence in which we say that the compiler or luxury tell the compiler to assign X to Y. So it will first store x inside y, then it will increment x. And order of operations is very important here. The postfix is basically doing the assigning using the equal sign. X will be assigned to y. Then it do or does the increment that we did here. So the final result will be x will equal 11, it will be increased by one. But the value of y will equal ten. Because when we first assign x to y, x value was ten, as you can see here. So ten will be stored inside Y, and this is the first part. The second part is basically incrementing x, so x plus blast. So x will become 11. Now, this is in the postfix. The prefix, however, will do something different. It will first increment x. As you can see, this is the first step. The second step, it will store that result from incrementing x and assign it to y. So incrementing x will result in 11. So x will equal 11. Then these 11, or the result as 11 will be stored inside y. So y will also equal 11. And you can see the difference between these results and these results. So what I need you to understand is in case you saw postfix, this means that you need to assign the variables first, then increment. But if you saw a prefix, it means that you first need to increment, then you need to assign the value. Same thing goes here. Here we have a postfix. So it will assign the value of x to y. So y will equal ten. Then it will decrement x by one. So x will equal nine. Same thing here. It will first decrement. So x will equal nine. Then it will solve that result inside y. So y would equal nine. You can see the difference between these four lines and these four lines this forward, very easy. It's simply incrementing or decrementing without its spot suffix or prefix. While in this case it's different. Now if it is postfix to last sign, then increment. If it is prefixed, it will increment then assign. You need to keep that in mind and take a note about. Now as usual to make things more clear, let's take a practical example. Now here you need to actually include that library. Then align the main function. Change the language to see. You all good to go. Let's call it. Let's call it unit. Now in here. So let's define x as give it a value of ten. And let's define y without giving it a value. Now, x plus, plus, plus, plus x, x minus minus minus minus x. These are the first four that we will test out. Now what I need to mention here is to make sure that we will get the right results. We need to assign x as ten after each operation to make sure that we are changing the value of x when it is ten. Because otherwise it will keep changing the value of X with the new value. So here, x will be 11, and this will be 12, this will be 11, this will be ten. We need to do these operations on the original value of X as an example. Now, let's print I will write the same thing, x plus last value equal percentage d. And let's add x. Now let's add a slash n here. As a new line. Let's copy this. Paste it here, here, and here. Now we will change this x minus minus, this will be minus minus x. This will be plus subplots of x. Now, let's talk about what will happen when we run this code. First. In this case, it will increase x by one, x plus, plus. So it will print here 11. Now x will go back to ten and will also increase it by one. So it will print 111 more time. X will go back to ten. It will decrease it by one. So x here will equal nine. It will go back to ten. It will increase it by one, then x will be nine as always. So 1111, line nine. Now let's try running this code. Gcc six arithmetic. You need to see, as you can see, x2 plus plus, plus plus x have the same result, 1111 minus minus, minus minus x, the same result which is line. Now, let's add a multi-line comment to this area. And do the other operations. We mentioned that we have y equals plus, plus, plus, plus. First. We need to print it. Now, we need to plan the values of x and y. So x value equals this. And after the slash n, y value equals this. So x and y. Let's add slash and here as well. And see where things will go. And another slash and slash. Now, this will print this, then it will go to a new line. We'll bring this to a new line with the value of x. And it will go. My new line to print this with a value of phi. That's it. Now we need to make sure that x value equals ten each time we run this command. Now, let's copy this base step as before, four times. Now this will be plus, plus x, which is the prefix. This is the postfix. This will be x minus minus, and this will be minus minus x. Let's call the base is three years. Copy this here, and copy this listed here. These are just the same unit operators that we explained earlier and we are just listing them out. Now if you want to split them, you can add this slash n to make sure that they are separated when they are printed. Now this will make the value of x equals ten each time before running the command to make sure that we are starting with the same initial value. Going back here. Let's combine the code being the screen, and run the code. As you can see, y equals x plus plus. Now, we don't know that the value of x is ten. And the first thing that this dead is to assign y to x. So y value will equal to, as you can see in here. The second step is incrementing x value will equal 11. Let's go here. This is a prefix, so it will first increment x. So x value will be 11. Then it will add the 11 to y. So y value will be 11. Just as we explained. Now, when it comes to these two x minus minus, this is a postfix. First, assign the value of x to y. So y will equal ten. Then it will decrement x by one. So x will equal nine. Going here. This is a prefix, so it will first decrement x. X value will equal nine, then we'll store the nine inside y. So y will equal nine. As you can see, this is a live demonstration of the equations that we introduced in this lesson. Now if you have any issue with any of these, I'll be more than happy to explain them in more details to help you understand. These are very important. Potatoes. They are widely used and you need to understand them all. If you are using the calculator without assigning using an equal sign, the postfix will be treated just like the prefix. It will be, there will be no difference. But if you are dealing with them with the equal sign, the postfix is different than that prefix. Postfix will first assigned operators, then increment, while the prefix will first increment, then assign the operators. That's it for this lesson. If you have any questions please ask and if you're on the board, I'll be more than happy to help. 15. Bitwise Operators in C: Hello and welcome to this new lesson in which we're going to talk about the bitwise operators. Now, the bitwise operators are used to manipulate bits inside C language. Now, let's start with the AND, or, OR and NOT. As you can see from these tables, when you see the unseen. This means that whenever there is 0, the result will be 0. So if we have two operands, a and b, a and b equals y 00, y equals 0. Since here we have a 0, it will equal 0 as well. And since here we have a 0 equals 0 as well, the only time that the result will be one is when both of the operands is one. So 11 equals one when it comes to the Order table. Now, let's talk about the order. Now it comes to the old. You'll usually see this sign between the two operands a. Now for the end, you will see the unsigned, so it will be a and b. In case of all, whenever you see one, the final result will be one. So here we have a one and times that will be one. Here we have one and the final result will be one. Here we have two ones. This one and this one. And the final result will be one as well. Now the only case that the result will be 0. There are no one's at all, neither a or B R1. So the final result will be 0, which is basically the opposite of that and almost oxygen, okay? Now for the XOR, as you can see in here, the x or is basically this sine a x or b. In this case, if the two are brands are similar, the result will be 0, as you can see in here. And then if they are different, the result will be one. Now, the last one, which is the easiest one, it's done at sine. Sine is a union operator. These are by operator because they take two operands. As we already mentioned, this is an integrator, So we will see not a nut means the inverse of a. If it is 0, it will become one. If it is one, it will become 0. That's it. Now, let's see them in action. Let's say that we have two values, x and y. X here equals 1010. Y is 0101, and these are binary values. And we can talk about binaries at the end of this course. Now, these two are the two values that we will do these operators and or not and XOR. Now when you are doing the end x and y, the final result will look like this. We already mentioned that the and sign means if there is 0, then the final result will be 0. So when we are talking about the end 01, we can do this to see the value of 01 on equal 010 equals 001 will equal 010 equals here. So the final result here will be 0. As we saw in the throat there. Now, regarding the dimension that this is the r sine. Now if we there is one, then the final result will be one. So 01110, only 01110 and also equal one. So it will be either a binary value, 14 ones. All we can convert it to decimal value using the calculator. Now, you can change the calculator to poor grammar. And you can enter the binary value 1111. And as you can see that decimal value is 50. So this equals 50. Now they're not sign is straightforward. Not x means this is the sign. Not, NOT x means the inverse of x. So it will be 1010 since. Equals 0101. And we can use the calculator to convert the value. We can write 1010, which is the original value. It equals ten in decimal. So let's try the new value correctly. Now let's add 0101. As you can see, it equals five. So this will be five in this. I need you to memorize these values because we will do this in a practical way and few seconds. And we need to know that. Now x, XOR y, we already mentioned that if they are both identical, then the value will be 0. If they are different, the value will be one. Since all of these are different, 01100110, then the final result will be the same as here, 1111, which equals 15 in decimal. Now we can do our last one about lumbering systems. But this is like a prerequisite for this course. That's it for the bitwise operators. Now, to make things more clear, we need to take a quick example. So let's move on. Now. Let's start by writing our include voids as use one main void. The language to see. In here, we knew we need to define the values. So x will equal the binary value of 1010. If you wrote it like this, it will treat it as a decimal value. So to me, the compiler understand that it is a binary value. You need to write 0 b. 0 b means binary. This is the prefix for the binary. Now we need to add Y as well. So 001, 01. Now, once you are done, we need to start defining new variables, ends. And operator equals x and y. And OR operator equals X or Y. And X OR operator equals x. The power of sine y. And NOT operator equals naught sine x. Now let's blend this out using a print f function. So I will write them equals percentage d. And that's the result here. Slash n here. Colby this line based the tears, tears and paste it here. This was this NOT x OR operator, and the equation change the Autopilot of the equation. Now, let's save it. Bitwise operators. Let's try to run this. Now. Let's swollen gcc c e x. Now as you can see here, we have 01515, which is something we expected. And here we have minus 11. Now let's talk about the minus 11. Now, at this level, we won't go into depth of the minus values. But let me show you on the calculator what will happen. Now the value is 1010. Once you choose the bitwise NOT operator, you will see that the decimal result will be minus 11. And this is because the 1010 or not treated on their own. The binary operation not is done on all the bytes that are left. So yes, you did write 1010, but the rest of the bits were written as zeros. And in this case they're not. We'll reverse them to one. Now in the coming lessons, we will cover the negative values and how to print them, and how to interpret them inside your console window. But at this point, what you need to understand is that when we did the NOT function, we did it only on four bits. We didn't take into consideration how many bits or bytes the compiler will assign for the NOT operator. So if it has assigned one byte, then the final result will be 10101111. Because one byte means eight bits and original value is 0101. These are only four bits. Bits. There is also four zeros that are hidden here. So we convert them to one. Now, other compilers assigned four bytes for an integer. And then this case we will have three more bytes of ones. That's why this is an advanced topic and we will cover it in the coming lessons. Now, if you reach this point and you are able to apply the and OR XOR and learned how to apply the NOT operator. Then you are good to go. Thanks for watching this lesson. Next, we will talk about more bitwise operators that are advanced and used in bit manipulation. But that's it for this lesson. 16. Bitwise Shift Operators in C : Hello and welcome to this new lesson in new trial going to talk about two more bitwise operators, the right shift and left shift operators. Now, the right shift operator is basically these two signs. And the left shift operator is these two sides. Now, x, right shift by one, or y left shift by one. Now when we say alright shift or left shift, we mean this in a bit wise level. So let's say that we have this. And let's assume that the width is only one byte, which equals eight bits. Eight bits, sorry. Now, these are our eight bits in one week, 12341234. This assumed that this is x, and let's make x equal ten. Now, ten in binary will be stored inside this. This is an eight bits variable that will take the value ten. Now ten is in decimal, not in binary. Ten equals 100101, and the rest will be zeros. This is the number in binary and associated number is ten in decimal. So let's store the value of 01010000. Now when we say x, right, shift by one, it means that we need to shift all of these eight bits to the right by one. So this will be moved here, and this will be moved in this place. This would be often this place, and so on. Now, we will have an empty bit here and we'll take a default value of 0. So the final result will be 10100000. This is the right shift. We did shift all of these bits to the right by one. So we lost this 0. This 0 was written here. And basically there is nothing here and it will be gone. So the first bit here will be the one because we shifted it by one. And the third bit will be the second one, the fault will be the third, and so on. Now if we executed right shift by two, means that we are shifting each of these bits two digits to the right. So this 0 would be moved twice. This one would be moved twice. So if we move this 0 twice to be out, if we move this 0 to one, this is one twice. It will move to here. This is one and then two here. This is the other one. So this one will go away and this one would go away as well. So start with 01, and the rest of these bits will be zeros. This is when we write shift by two. This is when we right shift by one. Now what about left shifting? Now when we do the left shift, It's basically the same principle. Let's copy this area and let's paste it. We're live here. Let's draw this most time with the same value. Let's add 01010000. Now what we need to do is to left shift. Let's say that this is called Why We need to left shift y by one. So if we left shifted this by one, this will be moved here, this will be moved here, and so on. And we will end up with this place as an empty place. So let's add 0 and empty place. Once we are done, we will lift, shift all of these so it will be 0101000. So we lost this 0. Now, let's talk about moving it twice to the left. Now here we moved it once and we have this block, loved ones to the left. So that's, that's why we have it here. Now if we want to move it twice, we will add 00. Then we will add this block, 010100. Does you can see this is the log that we are focusing on. Now this value will be moved twice, so it will be here. This value will be moved twice from here to here, and from here to here. And this is why you can find it here. So this is the meaning of fried shift and left shift. And this is how it's done in beds level. Now we will do it in C using decimal values. Now to do it first, we need to understand how to treat decimal values and how to deal with them. And we will have a separate lesson for that, as we already mentioned. But for now we will use the calculator. Now, let's take the same example. Include a CDI or the texts. And then here void main. Void. Change the language to see inside here, let's two variables. Now, let's define x as an eight bit binary number. So at 0 be 00001010. Let's define y as well as the prefix of a binary number. If you wrote the number without the 0 b, it will be considered as a decimal, which is the default number. Numbering system inside z. Z will be 00000101. This is y. Now let's use the right shift. Right shape. So integers, right? Shift equals the value of x, right shifted by 14. Lift shift the value of y left shifted by one. Now, let's blend the values. Then. Let's add the equation equals person d slash n. And here, add right shift. Now copy the same line, paste it here, and change the equation with y lift shift and left shift. Now, let's call this bitwise shift. Now, let's explain what will happen here. Now this will be right shifted by one. So the final result will be, will look something like this. 0 will be 000101. There will be a plus 0 here. So we will have five zeros and ones, one because we write shifted this, so this will move to the right one and it will disappear. This will be the first bit, as we already explained. And all of these bits will be right shifted by one. So we will have this as an empty place and the eight bit value and will be replaced with 0. Now this one will be left shifted. So the one will move to the left by one. So we'll have an empty place here. So in this case we will add 0, B 000010100 will be added here because all of these bits will be left shifted by one. So the final value will be this. Now let's convert it to decimal using that calculator. Here it is. Let's add that decimal value, or the binary value of 0 is 0, 00101101 here equals five in the salon. So five. Now let's clean. Let's add 1010 equals ten in decimal. So this will be ten. Now, this is after doing the right shift and doing the left shift. Now let's save their work. And let's open up cmd to see if this matches our calculations. So write GCC. See that, see, now it shows us that there's a problem here. We forgot to add the hash sign. So CLRS now edit. As you can see, x shifted by one equals five, which is this value, y left shifted by one equals ten, which is this value. And this is how you deal with the right shift and left shift operators. Again, you can write shifts or left shift by 12345 or any number of you want. The number here indicates the number of shifts to the right or to the left. And the signs show you that I election, this is derived, this is to the left. Now if you added one, only one sign, it won't be a shift or a bitwise operator. It will be a greater than or less than operator. So make sure that you don't misuse this. Again, it can be executed easily using this command, this command. And the other thing that I wanted to mention is that NC, when you are initializing a variable, if you add a 0, B means that you have to add eight bits after that, indicate that this is a binary numbers. 0, B is for binary. Now we also have 0 x four hexadecimal, but this is something we will talk about and the numbering systems lesson. And if you lift it to the default, she will initialize the variable equals 55 will be the decimal value because it doesn't have any prefix, which is the default value and see, and the most used value. And see. Now I just introduced the binary values because we need them for that bitwise operator, right shift and left shift. 17. Assignment Operators: Hello and welcome to this new lesson. No child going to discuss assignment operators. Assignment operators are used to assign different values using different operators. Some of the operators we already talked in previous types operators. The first one is the assignment operator. It's a very straightforward one. It's basically the equal sign. And here we are assigning the value of 20 to the variable x. Here we have an assign the plus equals sign. This can be interpreted to x equals x plus three. What this will do is add three to X value and assign the final result to x. So in this case, if X equals ten, which is the previous value of x, then plus three equals 1313 will be stored inside X as the new value. We usually use the blast equal three to short this equation into the US onto this shape. Now, same thing goes for all of these equations. X minus equal four is basically x equals x minus four. If x is ten, then ten minus four is six. So the value of six, which is the result of this, will be stored inside X. So X value will be updated and become six. Now, going here, x equals x multiplied by five. X equal the original value of x is 1010 multiplied by five equals 50. So x will equal 50. This will be the new value of x. If we went down here to the last one, AX equals X divided by two. So ten divided by two is 55 will be stored inside X. So the new value of X will be five. This is the short form of this equation. This is the short form of this equation, and this is a short form of this equation. Now, we also have the same thing for the bitwise operators and or not. And we have it for that mode. Or the person to sign operator. Now, x equal one, it means X equals x and one. And since we are dealing with when you are using AND or, OR XOR, we are dealing with x as a binary number. It will equal 0101. And we want to add one with this. It will be one here. So the final result will be 1101. So three plus ten equals thirsty. So the final result will be 13. Now, the same thing goes for the r and x, or x equals x, or x equals x. The x or sine two. You need to convert 15 to the binary form, 010115 equals 1111. This is x value, which is ten, and this is 15. The final value. You have to offer them. 01 equals 1111. So the final value will be 15 as one. So x one equal 15. Already mentioned how to do this and bitwise operators lesson. Now, the XSOAR is the same case. You need to add the value of x, which is the original value equals ten. Two is 0100. Now we already mentioned that if they are identical, the result will be 0. And here the result will be 0. Here the result will be 0. Here it will be one. So the final result for x will be eight. So x equals eight as a final result. This is the result of the XOR operation. You can use the calculator to make sure of the numbers. Or you can watch the lesson that we will add to the end of this course. That is called numbering system. In case if you are interested to learn how to convert binary into decimal without using a calculator. Now, the last equation here is x equals x mod or percentage. For. Now we already know that x value is ten. And we mentioned that you need to divide it by four. So ten divided by four equals two. Now, two multiplied by four equals eight. Then minus eight, which is the original value, minus eight, which is the result of the multiplication, will equal the remainder, which is two. So the answer here will be two. X will equal to. And I should ask, showed you how to calculate it. First, you need to turn this into our normal division, ten divided by four. It will equal to, without fractions, you want using division, there are no fractions. Now, to note that in mind that we need to multiply the result without fraction by the division factor, which is for the result will be eight. And then we subtract the original value, which is 104 x minus eight, which is this value. That isn't would be the reminder, which is two, x equals two. Now, the last two assignment operators are the shift right? And shift lift. Now when we write it like that x shift right by one, we are applying, right shift to x by one and assigning the value to x. So it's like writing x equals x, right? Shift by one. Same thing here, x equals x left shift by one without using the equal sign. And this is a very important thing to know. As you can see in this lesson, we learned the assign, the ad and assign plus, equals, minus, equals, multiply, divide and OR XOR and the modulus. We also then the right shift and left shift. Now let's do a quick practical implementation for these values to see the results. Now, first we need to include the library as usual. Then void main. Void. Change the language to see. And let's define x equals ten. Now let's call this assignment operators. Now, we already mentioned that we need to try all of the assignments that we just mentioned. The first one is x equals ten. We just tried it, the sign. Then we have x plus five. X minus equal three. X multiplication equal five. X division equal to. And we have the x and equal, let's say one, x equal one, x, x equal one. And we also have a right shift by one, x left shift by one. And we have the modes sign equal to. Now, what I mentioned that we must reinitialize x after each of these operations. This is something you must do to make sure that you are getting the right results. So let's do this here as well. Well done. Now this one here. And blend the values. So print f. Let's add person through D and X. Now here I will add the equation. But let's first copy this. I'm just doing this so that we can see the final results. For each of these operation, that's it. Now we just need to copy these equations inside. The double quotations. Done. That's it. We just need this equation here as well. Plus equal. Now, let's try running this program. Now, GCC, let's zoom in nine, assign operator or the C, E. And here we have the results. Now ten plus equal five equals 15, minus equal three equals seven, then multiplied by five equals 50, then divided by two equals five. X equals two. I think this is the percentage sign. Now to get to try to add a dimension that you need to try to twice. Let's clear the screen, compile again and run. Now x mod two, mod two equals 0. Since it's ten divided by two. The reminder, now, x equal one equals 0, x or equal one equals 11. You can check it out yourself. X, XOR one equals 11, x, right? Shifted by one equals ten, and x left shifted by one equals ten. Now, all of the results are correct, except for the last two, the right shift and left shift operators. Now in some compilers, x shift left by one and right shift by one or not recognize unless you add the assignment operator, which is the equal sign. So to fix this, you need to go back to your code and write x equal. X equal. Now, this will solve the issue and the GCC compiler, other compilers will execute it as it is and show you the right result. Now, let's compile again. See you again now as you can see in here, x shift left to the right plus ten in both cases, which is the wrong value. Now here, x shifted, left shifted here equals five here equals 20, which is the right value. Since we added the assignment operator. Now, these are all of the assignment operators that you need to know. If you have any questions about any of them or you fail to implement any of them. We are here to help. Thanks for watching this lesson. This is Ashraf from educational engineering team. 18. Logical and Relational Operators: Hello and welcome to this new lesson in which you are going to talk about rational operators and true and false and z. Now, in C, any number that is not equal to 0 is considered a true value. Five is true, minus 12 is true. False is true. As long as the value is not 0, then it will be treated as true. Regarding false. If the number equivalent to 0, then it will be treated as false. But you need to know that if there is a statement in C that returns true, the compiler is free to choose the value of the true. What's the role that must be any number except 0? This is a good piece of information that you must keep in mind when dealing with relational operators and logical operators. Now, relational operators are basically operators that check equality or equality, or more than or equal, less than or equal. And these things that are used in if statements or conditional statements that we will cover later. So relational operators checks the relationship between two values by determining whether it's true or false. Now, if x bar, if x equals ten, and y equals five. Like in this statement. This is a question. Checks if x equals y, this statement will return either true or false. Now, since x and y are not equal, it will return false. And we already mentioned that falls equals 0. Now, if you want to not equal, this is a sign. Now, this will check not equality. X is not equal to y. It will return true. And since x is ten, y is five, then this will return true. The third one is statement that will check a more than. So it will check if X is more than y. And x here is ten, it's more than y, which is five. So this will return true as well. This will check more than or equal. So if X is more than or equal, it will return true and it is more than Y. So this will also checks as true. Here. It will check if x is less than y, which is not true, so it will be false. This will check if x is less than or equal y. And this is not true. So it will check as false. You need to take an OT. If you want to test and print a false value, it will print 0. However, if you taste to print true value, the value is chosen by the compiler. Frequently it is either one or 255. We will check this in a minute once we reach the practical section of this lesson. Now, let's move on to that logical operators. The ones that we covered here are called relational operators or relational operators. Here we have the logical operators. The logical operators are used in applying logical operations between two values in which each are considered either true, which is not 0, or false which is 0. So we have the logical and as you can see here, then as you can and is written by writing to the logical OR is written by writing to or signs. Now, now, the logical NOT. Now the logical not in here. X equals not fall. Since four is true because it doesn't equal 0, then not true equals false, then x equals 0. Now, to test this out, Let's explain the logical AND, and OR before moving to the practical section. Now here we have three which is true. We have 0 which is false. We know that if that is true, which is one and false which is 0. And the and operator, then the result will be 0 from the truth table that we discussed earlier. Now here, 0 means 0, which is false. Three means through which is 110. When it comes to the ord function, it will give us one. So it will be either one or 255, which interprets as true. In this case, four is true and not true, equals false, which equals 0. These are the logical operators and the ones before them were the relational operators. Now let's see how we can implement them inside our compiler. Let's first include in the library and write void main. Void. Now in here, change the language to see. And this are writing the lines. I will print them directly inside the print f function. So here we will deal with each of them. So let's say that we want to start with the equal x. Equal equal one is defined x and y as the two variables. Now, x equal equal y, n will equal percentage d, and we will add the results in here. So we'll add x equal equal one. Now you can either do this or you can simply add this new variable here. Let's call it m and the value inside M, Then trend. But to reduce the number of lines inside our code, I will use this and instead, and save one line. That's it. Now Save, let's call it rational. Now, let's copy this line. Basic tiers. We need six lines or six relational operators. And we need three lines for the logical operators. So this will be x and, and, and, and as well. This will be all. This will be not x. So it will be the same here, not x. Now here it will be equal, equal. Not equal will be greater than or equal, less than. Less than or equal. Greater than. I'm writing the same things that we just saw on the table. Just to see how the results will print slash and made sure that each of these lines will be printed separately in a new line. Now that's it. Let's see if it will print out or not. And we can an issue when we now G, C, N logic brush. And let's see, now a e x e. As you can see here, we have the true and false. Now let's shake them out. X equal equal y. So they are not equal. It would be false, which is 0, x naught equal y, it will be true, which is one. X is greater than one through ten is greater than five, so it will be one is greater or equal than y. That is also true. It will equal one. X is less than y. It's false. So 0, x is less than or equal. Why it's false? So 0 again, x and y. Now we already mentioned that and, and why? We'll ask if x is true and y is true. Now, x equals ten, which is true, y equals five, which is true, that none of them equals 0. So true and true equals true. Now regarding the whole operation, x equals ten and y equals five. Now we have an error here. It's printing 0 because we haven't changed this in here. So we need to change it, save the code again. Go back, clear. Sorting. By then. And here it is. True or true equals true. Now, not x, since x equals ten, which is true, not true equals false. And these first six here, logical, sorry, the relational operators. And the last three are the logical operators. That's it. We're done with the operators in C. If you have any question about any of these operators, I'll be more than happy to help answer all of your concerns and questions. Just ask. Thanks for watching this lesson. This is Ashraf from education engineering team. 19. Conditional Statement if in C: Hello and welcome this new lesson in which are going to talk about conditional statements in C. Conditional statements executes operations under specific conditions. There are two main types of conditional statements in C. That IF statement, the switch statement. The one that we'll start with today, is the if statements. Now, if statement is basically a type of conditional statements that you can use to check if a condition is true or not. And depending on whether this condition is true or not, you can execute a specific piece of code. Now, let's talk about the syntax. Always make sure that you have the syntax file, then you start recording process. We will talk in this lesson about the first case, which is only if condition without else, if or else. Now, the syntax is as follow. You will write f and you will write two indices. Now between the two parentheses you write your condition like x is greater than y, for example. Then you would add two curly braces. Between these two curly braces, you write your code or the action that you want to execute. If the condition is true, then execute this action. Otherwise this action won't be executed. Now, to make things more clear, Let's see this in action. Now, let's include our main file. I'll use one. And let's add the main function. Now in here, you can easily write anything. Let's initialize a new variable and give it an initial value of 50, change the language to C. Now we will use f statements. This is the syntax. If two parentheses and two curly braces. Now press Enter here as usual, and between the two curly braces. Now this is where you will write your codes or the action. And here you will write the condition. Now we will write a logical or rational condition if x greater than or equal 50. So this is the condition and we know that it is true because x equals 50. Now we will print statements. X is greater than or equal 50. That's it. If this condition is true, it will execute this line. Otherwise want executed. Now, let's save the codes. Let's compile it. Now this is one, n is gcc c. Now, a lot explore. As you can see, the action was executed because the condition is true. Now, if we change the condition to make it false, Let's make it takes less than 50. Now, you can go back here. You can compile the code again and run the EXE. As you can see, when you run edit EXE, nothing is printed because this condition is false. So the code inside the two curly braces will not be executed. And this is the whole point from using f statement. So if the condition is true, execute the code between these two curly braces. Otherwise don't execute it. That's it for the if statement. This is the first case. In the next lesson, we will cover the second third cases for if statements. If you have any questions, feel free to ask. This is Ashraf from educational engineering team. 20. Conditional Statement else if and else in C: Hello and welcome to this new lesson in which we're going to talk about that second, third case of if statements. Now, in this case we have something called else-if. Let's check it out. This is something we are already familiar with from the first case. If condition then execute the action. Now, if this condition is false and you want to check another condition, in this case, you need to add else and leave a space, then add f. You will use the very same syntax. As you can see in this area. If that condition is true, then execute this action. The only thing that's new here is the L statement. Now, else here means that if this condition is not true, then go and check the other condition. But if this condition is true, then you shouldn't go and check other conditions. You need to make sure that you understand this point well. If you added else, it means that the first condition that will be true will mean that the program will execute the associated action and will not check other conditions. Otherwise, you can use only f and you can get rid of the else if you want to check all of these conditions. So in this case, if condition is true, condition one true, it will not go and check condition too. But if condition one is false, it will go and check condition two if there is an else statement before the F. Now, let's see this in action. Now let's use the same code from before. This is f, x is less than 50. Then go right else if two parenthesis and two curly braces. Now here we will check if X is above or equal 50. Then in this case, we will print this so x is less than 50. Or else, if this condition is false, then go and check this condition. If greater than or equal to 50, then print this line. This is the use case of elseif. It will check this condition. If it is true, it will not check this condition. It will just execute this line and this will go out of the if else statements. But if this condition is false, it will check the second condition. If we have other conditions, and this condition is false, it will check the next condition, and so on. But you need to add the else statement before the F. Now, if you need the program to check all of these conditions, even if this is true and you didn't check this one as well, you will need to remove the else statement. And it will check the first condition. Then it will go and check the second condition. And to go and check the third condition and whatever f statements that you added. But we usually use the else statement to reduce less CPU load and to reduce the amount of lines that we need to check and execute. So if this is true, there is no need to check this. Now let's try and execute this code in here by GCC 11. Condition if else state dot c. Right. Now as you can see it printed, x is greater than or equal 50, which is this line. What happened here is that the program went through this one. It checked if x is less than 50, and this is false. So what happened here is that it didn't execute the print f function because this is false. It went to the second condition. Else, if x is greater than or equal 50, and this was true. So it executed this line, and this is what you see here. Now that leads us to the third case. The third case is simply the else case. In this case, this is as a line of code that you write to make sure that if none of the conditions is true, it will do something else. So if condition one is false, else if condition two is false, else if condition three is false, then go and execute whatever is inside the else statement. You just write else and add two curly braces. Now to apply this to our code, you can simply go to the code. And in here, you can write else and add two curly braces. Now between these two curly braces, you can write a print f function. None of the condition is true. Now let's make all of them false. So let's make it x is greater than or equal to 60. So this one is false. Else if this one is also false, so it will go and execute whatever we wrote inside the else statement. Save your code, will go to the console window. Now let's compile the code needed a screen, hey, the EXP. And here it is. None of the conditions is true because the first condition is false. It went to the second condition. Else, if 50 is greater than or equal, 60 is also false. So at least it lifts that second condition and went directly to the else statement and executed the code inside this else statement is like a default case. If none of the condition is true, you need to write something inside here to show to the user, like if he wrote our own password for a specific number of times or the wrong password. I have checked using if and else if statements for different passwords that you have set, then you can write none of the passwords is true. And this is one of the use cases, L statement. It can also be used without the elsif. So you can simply remove these two lines and leave it just if and else. And it will work without any problems. That's it for this lesson. Now, to summarize things, F is used to check a condition. If you have more than one condition related to the same variable, you can use if and else if statements. If you have an action that you need to execute, if none of the conditions is true, then you can write it inside the else statement between the two curly braces. And it will be executed if none of the conditions is true. One last note is F. F statement is true. It will not go through the else if and else statements. It will just execute this action and get out of the if, else, if and else block. This is a good way to reduce the amount of time spent on checking the conditions. So if this condition is true, it will not check this condition and will not go to the else statement. We mentioned that if you want it to check all of the conditions, you need to remove the else statement from here. And it will be just a normal if statement that checks the condition. If the condition is true, it will execute the action. That's it for this lesson. If you have any questions regarding the if and else if statements, I'll be more than happy to help. Thanks for watching this is Ashraf from education engineering team. 21. Local Variables and Global Variables: Hello and welcome to this new lesson in which are going to talk about local variables and global variable. This is a very important concept when programming in any language, not just in C. Now, let's talk about local variable. A local variable is the variable that is defined inside any function. This variable can be accessed only on the function that defines it. So as you can see here, we have a local variable. It's integer x equals ten. So let's type is integer, the variable name is x and the value is ten. Now this function can only be accessed unseen inside the funk. See, this is the only function that sees this variable. This is why we call it local variable. Now, the local variable can be seen only between the two curly braces on which it was defined. So as you can see from here to here, That's why it's called local. Now, the global variable, on the other hand, is the variable that is defined outside a function. This variable can be accessed in any function in the code. So let's take a look to the right here. We have integer x, and it's defined outside the main function and outside function one. Since it's defined outside of them, it can be accessed by the mean and can be accessed by func one. And this is our grid. Global variables are, they can be used anywhere inside your code. That's why they are called global. So whenever you want to create a variable and use it inside more than one function, you need to create it outside the functions at the beginning of your codes, usually after the hash include. But if you want a variable to be accessed only inside the specific function, then create inside the function itself. And in this case, it will be a local variable. Now to make things more clear, let's take a practical example. Let's create a new project, actual fluid. Now, void, main void. Go to the language C. C. Let's save that. Let's call it locally. Now, let's create a variable here, x equal ten. Let's now I planted the regular way x. This is the file name. Now if you tried to execute this code, it will execute without any problem with this is a local variable and can only be accessed in between these two curly braces. Now if we were to create another function, this is the function prototype and x void. Now let's make the implementation here. The same line. Print f x. As you can see, this will try to print the variable x, even though it wasn't defined in this group. And even though it is a local variable. And we already mentioned that this function will have no access to this variable since it is a local variable. So let's call the function when x. So this is the prototype, as we mentioned, this is the implementation and this is the function form. Now save the codes. Go to File Cmd, G, C, C. Okay, now let's look at this error. Function. Print x. X is undeclared. And this is because we are trying to access a local variable that was created inside the main function, inside another function. And this is not possible because this is a local variable. Now, let's create a global variable. Here, int y equal 15. And let's add y here. So this will print the local variable, and this is our global variable. Now going back to the C code, it will compile without any problem, as you can see. Now, how about E? And it will print x and y. Now y can be asked in the main function and in print x function. Because it's a global variable. While x can be on or can only be accessed inside the main function. And this is the main concept of local variables and global variables. Fast rushing this last one, this is Ashraf from educational engineering team. 22. General Rules Regarding if statement: Hello and welcome to this new lesson in which are going to talk about some general rules when dealing with if statements. Now, the first rule is that else if and else are optional. Now you can use if statements without having to write else, if else, if you have only one condition to check. These are optional add-ons that you can use depending on the use case or the end goal. Nested IF is allowed. This the diff is basically writing an if statement inside another FCC. And I'll show you that in a minute. It is not allowed to write code between f and f or else. Because if you did write code, you will be separating the F from the else if statement. And it will show you a syntax error. Use round brackets to an if statement with several conditions to avoid technical errors. Some people use the f statements without fighting the curly braces or round brackets, which goes a lot of syntax and technical errors. And I'll talk about that in a minute. In case you only need one action in a multiple condition if statement, you may opt to not use a bracket, although it is still highly recommended. Now, let's see these nodes in action. Now let's fight and new code. Let's add the main function. And let's choose the C language as our default styles. Now, int x equals 50. We need to check if x equals one. Inside here we would write if x is greater than or equal 50. Now between the two curly braces, we will use print f function. And in here we will lie x, The equals 50. Now, what we meant with the fact that else and else, if our optional is that you can choose not to use them and there will be no errors, no syntax errors, and nothing. What we meant with nested F is that you can write another if statement inside this if statement between these two curly braces. So you can go after this print f line and check using another if condition if x. Let's say that here we are checking if x equals 50 greater than, let's say 50. Let's make it 60. And inside it, we need to check if equal, if x equals 50. Let's say this will be our code. So we will print the same line. X is greater than 50, and here x equals 50. Now this f statement, as you can see, these are the two curly braces and read for the first if statement. Now inside it, we wrote another if statement, and these are the curly braces for the second if statement. And this is something we call nested IF, which is writing an if statement inside another if statement. Now, this is allowed and you can do it, and most of us do it to check multiple conditions. So when the first condition is true, we need to check if the second condition is true inside the first condition. Now, this is the print F function that will be executed if x is greater than 50, which is the first condition. Now inside the second condition we add another print f function. So if x equals 50 or let's say 55, in this case, it will print the second function, which is the print f function. Now, let's try and execute this. Let's call this F fools. Now open containing folder and run it with C and D. Now here we will add g, C, C, E, E. As you can see, x is greater than 50 because x equals 6060. But since x is not, o does not equal 55, it didn't grant the second if statement. Let's change this with 16. What will happen? Executed and run? As you can see here, the first condition is true, x is greater than 50. So it printed this line inside the if statement. And inside we have another if statement inside the first if statement, which is stdev. This if statement will check if x equals, equals 60, and that is true. It will execute the second print f statement and it printed x equals 55. This is how to use nested F. Again, this is an if statement inside the if statement. As you can see, This is the first if statement, and this is the second if statement inside it. It's not like the else-if case. Now. It is not allowed to write a code between the f x equals ten. And let's add anything inside here. It's not allowed to write codes between this curly braces and the else if statement like this. If you try to write, let's say a print f statement outside that first if statement and before the else if. Let's try to execute our code. As you can see, we have an error. We have ends without a previous f. So it's indicating the else-if statement, which is this statement. This is because we added a line between them first if statement and the else-if statements. So this new line breaks the block that if and else-if block. So this if statement is one block, this else-if statement is another block. And you cannot use else if or else without an original IF statement. That's why there is an error that else without a previous f is detected and it showed you act syntax error. To fix it, you need to remove this and make them stick together. And this will be treated as a block. Now, another thing is that you can use this else if statement without these two curly braces. You can remove them. And you can just drive this f print f line. Now, I don't usually recommend this because it will give you a lot of technical errors and logical errors. Sometimes the code might work, but it will behave in our own way. We usually prefer to add the two curly braces after the if statement. But let's say some rules. If you want to use the F without the curly braces. The first law rule is that if you wrote the f without the curly braces, you are only allowed to add one line of code. To check this, Let's comment all of these lines. So I will add a comment here and here. And let's use this statement. Now. If x equals, equals ten, here you can write it x equals ten, and it will be executed. Now if you want, try and after line inside the if statement, x and deeds. If one step. Now, since you haven't added the two curly braces, that beginning at the beginning and the end of that action code. It will only execute this code. Now, let's check this inside the console window. Okay, now let's save the code. I haven't saved it. Now, it's saying that we have implicit declaration of cooking rent. We need to add F here. It's a spelling mistake. Now, let's execute this. As you can see, x equal, equal to n, and this is true. It executes the first line. The second line is not related to the if statement and it was executed anyway. Now let's make the condition wrong. So if x does not equal ten, now, let's compile and run. As you can see, even though x does not equal ten, it did executed the second line, which is the print f statement. X indeed equals ten. This is because if we haven't added curly braces, if will only take one line after the if statement and treat it as if it follows the if statements. So if x does not equal ten, that is not true. So this line will not be executed. This is the end boundary of the if statement. Since we haven't added the curly braces, this line is assembly line of code outside of the if statement. It's like you have written this line of code away from the IF statements. Because IF statement without the curly braces can only execute one line of code. Now if we wanted to execute both of these lines, we need to add the curly braces. Now, when we execute the code one more time, it will print nothing because these two lines are related to this if statement. Let's try this out. As you can see. It didn't print anything. As you can see, both of these lines following the if statement and it is false or no lines were printed. But in the case of no curly braces, it did print the second line. Because we already mentioned that without the curly braces, if will only take one line after the if statement and treat it as if it is the line of code or the action that it needs to execute or not execute, depending on the condition. Now, again, we don't recommend at all not using curly braces. Using curly braces is a good programming practice. Without them, you might end up having a lot of logical errors, but you need to know the specific inflammation because sometimes it comes in a multiple choice question or a quiz or exam or an interview. They will bite if statement without the curly braces and tell you what is the output of this program. Now you need to understand that the F is only related to this line of code. This line of code is not relevant to the epstein. That's it. That's watching this lesson. If you have any questions for him. This is Ashraf from education and engineering team. 23. Switch Statement in C: Lambda will come this new lesson in which we're going to talk about switch case. Now, switch statements is like if statements are used to check if a condition is true or not, then it will execute a command. Let's switch statement permits users to choose only one choice from a set of choices. The variable values are compared with the values and different cases. And then it matches the case value. In case there is no match, the default block is automatically executed. Now to make things more clear, let's take a quick look at this diagram. Here is our expression, which is basically the things that the variable that we want to check. Now, if this variable equals that first constant, let's say one. It will execute code block one. If it is not equal to one, it will go to check the second constant. Let's say that it is two. Now, if the variable value equals two, it will execute this block. Otherwise, it will go to the third constant. And it can go on and on up to n number of constants. Now, if none of these constants or conditions is true, it will go and execute the default code, like the L statement and the if else statement. So if none of the conditions is true, go and execute the default code. That's it. Now, to make things more clear, Let's see the syntax. First. Let's add that include statement. And that main function. Now, change the language to see save the code as 13 switch. Now, let's define a variable and x equal five. Okay, let's make it equal three. Now. Which case syntax? First, you need to add that switch and two parentheses and two curly braces. Then start striking the syntax for writing anything inside the two parentheses. Here you write case. And these two dots. Then you need to add break. The syntax is a little bit complex, but you need to memorize it as it is. Now. You need to add another case, depending on how many cases you need to add, another break, another case, and a little break. And then finally, you need to add the default and break. It's now, let's start by adding here the variable that we want to switch over, which is x. Now, this is the first case. So bite anything inside here, What makes sure that it is a constant? So let's live one. So if x equals one, then write your code here. Actually one. This is condition one. Let's say that we want to use print f to print function, to print something. Let's say x equals one. Now, copy the same thing. Here we have the seconds, which case? Make it to say x equals two. Here we have the third one. Make it three, and write x equals three. Now if none of them, Let's name this default action. And let's say that x value is negative. If none of these is true, then it will execute this line. Now, let's save this code. Let me explain the code blocks then we can talk about each of these parts. Now as you can see here, we have the switch statement. Now what I need to understand is that between these two curly braces, we must add a variable that we want to check. Now, there are two curly braces. Everything else is placed inside of them. Now the syntax is clear. We have a case and we must break it. Now, the case ends with two dots, while the break ends with a semicolon means one. Now, the case, there must be a space after the case, then you can add the value that you want to switch over. So this will check if x equals one. And if this is true, it will execute this action between the case and the brake. Now, if this is false, it will go to the next case. Now, if this is true, it will execute this and get out of the switch statement, just like the if, else if statement. Now, if this is false, false. Then it will go and check the second case. If x equals two. If x equals, equals two, it will execute this action. Then it will break from this case, and it will get out of the switch statement. Again, as you can see here, we have two dots. Here. We have a semicolon. Here we have a space between the case and the value that we want to check. Same thing for the third case. And you can add a fourth, fifth, and any number of cases. The last case will be the default case here. Now the default case here is basically the else statement in the if-else statement. Now, if none of these conditions is true, then it will go to the default case. Here we have two dots. And to execute the action or anything written between the default and the break, which is this line of code. It looks like an if, else, if and else statements, but using a switch case. And it's a very familiar or a very famous way to switch over a variable to check if it is the right variable or not. And they usually use it when you're creating a menu for the user to check an item form. Now going back to our code, let's save the code and try to compile it. Now here we have GCC 13 switch state. See a dot EXE. And as you can see, that this line was printed. And it was printed because x equals three. So once we enter the switch statement, it shaped if x equals one, this is false. So it went to the second case, if x equals two, which is o. So it went and checked if x equals two, which is false. And it went from this case to the next case to check if x equals three, which is true because x equals three. So it printed this line between the case and the break. And if we're not any other line inside here, it will be printed and executed. Once this or one of the cases is true, it will execute the code inside the case and it will get out of the switch statement. So it will not check the default and it will not execute the default. That's why we have x equals three. That's it. This is the switch statement and this is how to use it. If you have any questions regarding anything unhealthful ****. This is Ashraf from educational engineering team. 24. Switch Statement General Rules in C: Hello and welcome to this new lesson in which we are going to talk about switch statements. Rules. These are rules that you must take into consideration when you are dealing with switch statements. Now, we'll talk about that constant for each of these cases. Number 123. This constant must be unique, so you cannot use the same constant. Wife's like 11. This is wrong. You cannot add a variable here like y or x. Or a must be a constant value. Default label is optional. So you can use this default labeled with a break statement or you can delete it. The switch case statement will work without any issues. This is, I would point to keep in mind. Now, only one default is allowed. So you cannot add a default here and add a default here. This will give you a syntax error because it will disturb that program. It won't know which of these defaults to be executed. So we have only one default. Now, second thing about the default is that it can be placed anywhere inside the switch statement, so you can place it here. All you can place it here. As long as it's only one default, it is allowed to place it anywhere. So make sure that you add it whenever you want. Just make sure that it's not duplicated. Now, the break statement ends with a switch. Each of these cases much must have its own break statement. So in this case is true, will execute this code, then break that switch statement altogether. So it will get out of the whole statements. If you forget to add the break statement, this will cause logical errors. In case I break statement does not exist. Like if we remove this break statement, all subsequent codes shall be executed until the end of switch or until the program finds a break statement. So it will execute this, then go on to execute this until it reaches the break statement. Make sure that you don't forget any of the break statements. Each case must have its own break statement, and I usually buy the whole syntax first, then I start to code. Another good thing that you need to know is that nesting is allowed. And what we mean by nice thing is that you can write a switch statement inside of these cases. Let's say that we are inside case two. We can easily write switch case 0, a break. And we can add another variable here, let's say y and switch using this variable default. And after the default, we have that break. Now, this is allowed inside any of these cases, and this case is called nested switch statement. So it's piping switch statement inside that original switch statement. Now, to summarize, our case, constant must be unique and it cannot be a variable. A default label is optional. Only one default is allowed. However, it can be placed anywhere in the switch statement. A break statement ends the switch. In case I break statement does not exist, all subsequent codes shall be executed until the end of switch or finds a break statement. Nesting is also allowed. Just like we showed you a few seconds ago. These are the main rules that you need to keep in mind. Usually most of them come in multiple choice questions and true and false questions or interview questions regarding programming in C. If you have any questions about any of the things that we explained, I'll be more than happy to help that's watching this lesson. This is Ashraf from education and engineering team. 25. Do while loop in C: Hello and welcome this new lesson in which are going to discuss the do-while loop. Now, it is very similar to why Lu, but since we have ado before it, then there is some changes or some differences, let's say. Now let's look at the syntax. As you can see, it starts with ado, then two curly braces. Now, the condition is the last thing written here. As you can see, these are the two curly braces. Then we have the block of code. After that, we have that condition, which is why two parentheses. And between the two parentheses, we have the condition. And here we have a semicolon. Now this is the syntax and you must memorize it. Since we have the dual and we have the curly braces with a block of code prior to the while loop, the while condition. This means that the loop body statement will be executed at least once before checking whether the condition is true or not. This is because we have the condition here at the end. And this is the main difference between the while and do-while loop. So the do-while loop executes the code block prior to checking whether the condition is true. It will continue to repeat the loop for as long as the condition is true. Just like the while loop does shrink in this case. Let's see this example. Here we have an integer x equals one. We have due to statements and we have this condition. Now the first thing that will happen, it will go to the dual. Then it will execute these two lines before checking the condition. So it will print and scan, will print, I'm in the loop. Then it will scan something from the user, Let's say a number. Now while the number that was count is not equal 0. So what this condition is true? Just like in the while loop. It will go back and execute the code block again. Once it finishes the execution, it will go to the condition and it will keep looping like this, then like this, like this, then like this, and so on, until the condition is false. Just like what we explained in the while loop. Except that in this case, if the condition is false from the beginning, the code block will be executed at least once because we are executing the code block before even checking the condition without the condition is true or false. And this is because we are starting with the du, then the y. Unlike the wine, which is the second, the second time that we explained. Now, let's take a look at a practical example. First, let's include stdio.h edge void mail. Here we need to add voids. And let's choose the language to be c. And x equals one. Do while the condition is x not equal 0. This is the syntax. Now press Enter here. And here we need to add the code block. This add a print f statements inside the loop. Then scan f, read an input from the user. And let's say X percentage d. Okay, now let's say that enter x then slash and without the slash, and we will leave it like that and the same line. Now let's save it. Let's call it 16, do while. Now let's go to the compiling process. Now go to the file open containing folder CMD, gcc, c of x. We are inside the loop, enter X, so X, let's say 123456. As long as x is not equal to 0. It will keep doing that. Now once x equals 0. Now here's the condition. X naught equals 0. Now, if x is 0, so 0 equals 0, so this condition is false. It will get out of. The do-while loops. So let's write 0 here. As you can see, it's out. Now, let's say that we want to make the condition false from the beginning. So let's say that x not equal to 0. And here we have it. X equal one. Now, as you can see in this case. Now if we enter 0 here, let's go to execution. Now if we enter 0 here, means that 0 not equal 0. Now we already have this condition as false because x equal 11, not equal 0 is true. So if we replace this was 0, let's say we save the code. So this, if it is not a do-while, nothing will be printed. But since we are using a do-while, and we already mentioned that the code block will be printed prior to chicken without the condition is true or not. The condition is false. It's not true because as you can see here, 0 not equal 0 is false because 0 equals 0. So the condition is, and nothing should be executed. But since we are using a do-while, It will be executed at least once, even if the condition is false. So let's run it. As you can see, we are inside the loop, enter x. Even though the condition is false, we are getting the code block executed, as you can see in this line. And this is the main difference between the do-while and while. Now if we are using the same code, like this code, I will copy it as it is the wine. And here I will add the two lines, these two lines. Now let's comment this part that the wild. And let's play the wireless cell. Now if we save this code, go back to the execution. The screen. Now edit EXE. As you can see, nothing was printed here because the condition is false. Since we are checking the condition in the wild before executing anything, nothing was printed. But in the do-while, this was printed, even though the condition is wrong. This is the main difference between these two. I hope that now you are getting what I was trying to point out on Beck's explanation. Now, if you have any issue or any problem understanding the do-while, I'd be more than happy to elaborate. Questions on the assignments will follow to make you understand things even more. Thanks for watching this lesson. 26. Break and Continue in C: Hello and welcome to this new lesson in which are going to talk about break and continue. Now, break statement is basically writing break and adding a semicolon. Vague statement can be used with the loop to exit the loop immediately and execute the outside code starting after the loop. While the continue statement, which is basically writing continue, adding a semicolon. When skip the current iteration and jump to the next iteration. It will skip this code and go directly to the next iteration. The purpose of that break statement here is to break out of a loop. For example, if our code is asking I user or the input to enter an integral named x. And this condition is true. It will break the while loop. Now to make things more clear, let's take these two examples. This is an infinite loop. An infant who was basically a loop that will repeats forever. So this code will keep repeating forever. Because while one, and we already know that any number that is not 0 is true. One here means while true. This condition will be true forever. That's why we call it infinite loop. This loop will break once the user enter x as one. So it will weigh the user to enter something, anything. Now, if the thing that the user entered equals one, it will break from the loop. Now, that's it. The loop will end without having to make the condition false. Now for the continuous statement, let's say that this is a for loop that loops from one to nine. Since I is less than ten. Now, it will keep executing this code with each iteration, just like how we exit planned in the fourth lesson FOR loop lesson. Now, this statement, if I equal equal sex, will check once I or once the iteration reaches that six, or I equals six, it will kid this hydration. And when we say escape, it will not execute anything in here. It will just jump to the action and increase to seven. So this line will not be printed when i equal equal six. And this is what we mean by skipping I iteration using the continue statement. Now to make things more clear, Let's do this using a practical example. Now let's start by adding our hash include. As usual. Man, void. Now here between the two curly braces or curly braces. So we need to add our code. Let's show that anguish to see. Now, we need to create while loop this, the break sentence. Now inside this while loop, we need to make it infinite loop and we need to read input from the user. We will live person to D. And Let's say, let's create a variable, call it M, give it an initial value of 0. Now inside here we need to check if m equal, equal one. Then I can add it in the same line. Or if an alkyne, that method, as long as it's only one line, it will be executed without that curly braces, as we mentioned in previous lessons. Now, if you try to test this code, let's first save it. Now save the file. Go to File open containing folder cmd. Here. Let's zoom in. You'll see the filename. Continue to see. Now. As you can see, it's waiting for us to enter something. Let's enter five, then enter 678. It will keep asking for more to keep scanning the incoming value since we are inside an infertile. Now once I write down one, it will break from the while loop. And break statement basically is used to exit while loop immediately and execute the code outside, since we don't have any code, will go outside the while loop and finish the problem. Let's try one. Enter. As you can see, now it's out. So it went outside the while loop and the program finished executing. So this is the main purpose for using the brake line. That's basically to break out from all the safe infinite loop condition. Now, this is the first thing. Let's continue statement using a for loop. So here's our four inside here. And I equals 0. I is less than ten plus a plus. So here we are going to ask if I equal equal five. Then continue. Now, before moving forward, we need to add a print statement. Print f. Let's say percentage d slash n. In here we need to print the value of all. Now this line does not exist. Let's see the output in both cases without the continue on with the container. Now this will print values from 0 to nine. So let's go File Open. See Cmd, G, C, C, 17, brief tenure. Let's see. Maybe ten. You now ID EXE. We'll print values from 0 to nine. So 0123456789. Now if we enable this, once I equals five, this condition will be true. Continue, we'll skip this anything inside the loop, and it will go to the increment or the action block of the for loop. So it will not execute any code when it reaches that, I equal equal five. So five will not be printed. So let's test it out here. Let's save that code. Go back, combine it, executed. Now as you can see, let's convert them. Here you can see 01234, and here you can see them. Now five is here. And the previous execution without this sentence. While here we don't have five, we have on 6789. So it did skip five. Now we already mentioned that continue statement. We'll skip the current iteration and jump to the next iteration. And this is what happened here. That's it. This is the break statement out of a loop. If the condition is true, this is the continuous statement, which is basically a statement that is used to skip a specific iteration inside a loop. That's it for this lesson. If you have any questions, I'm here to help. Thanks for watching. 27. Functions in C: Hello and welcome to this new lesson, which is one of the most important lessons in this course. In this lesson, we will talk about functions. A function is a block of code which only runs when it's called. It is used to perform certain actions. And they are important for reusing code, like define a code once and use it many times. To use the function, you need to call it inside your code. When calling a function, you may send some data or some input, and it calls return back and out for you. The most common function is the main function, which is the entry point that we have been writing since the beginning of this course. Now, our wave function is basically this. We write it like that. Void main, two parentheses, and two curly braces. Now, this is the function name. And main is reserved for that main function, which is the entry point between the two parentheses, we add the inputs. Now if we don't want to add any inputs, we add the word void. Now this is the returning data type. If this function does not return anything, then we call it void. We add void in the return data type. And the code that you want to execute or reuse, you usually write it inside here. This is the codes. Now, this is one of the functions that we have been using a lot since the beginning of our program. To execute the function, you will need to call it. The function provides you with advantage that it is defined one time and can be executed many times. So it takes the same size in the memory, whatever, how many times it will be called. When you call a function, you can send to it some inputs, as we already mentioned. And the example for a function that we have been using since the beginning of our coding process is the print f function. Now print f function is basically a function that takes inputs between the two parentheses. And the execution of this function. Function will print output on cmd, which is the command line window. Now the print function takes a string as an input argument and print it on the screen. See projects composed of one function or more, which are basically the main print and scan. Now, print f, scan f mean. All of these are called C programming functions or built-in functions. Because we do not create this function, we only use them. We call them by their name. But if you create a function, let's call it, let's say that you call the function Ashraf. Then this is called a user defined function. So anything that you create is called user defined function. I think that you use, and it's already created by C compiler or C programming language, is called a built-in function or a C programming function. Now, to make things more clear, we need to talk about what should you do if you want to create your own function? Well, if you want to create your own function, you need to understand that a function consists of three parts, and you need to memorize these parts. The first part is the prototype. And this prototype declares the function. So it tells the compiler that there is a function with this name and these specifications. Usually the prototype includes the return type, as we already mentioned. The function name, parentheses here and there, and the input between the two parentheses. Then the line ends with a semicolon. This is called a prototype. Now, this is the first part. The second part is called the implementation. And it's basically the place where you write the function code, defines the function behavior. And it has the very same shape as the prototype, as you can see, except for the same column here, we don't have semicolon. Instead we have the two curly braces. Inside them. We will write the function code. And you can see that here. Here we have the first curly brace. Here we have the second. And between them. We usually write our function statement or code. Now, this is the second part, which is basically writing down the function itself with the code that we need to execute. Now the third bark is the function call. The function call includes the function name and any impulse between the two curly, the two parentheses. And if it returns something, we need to store the data that this function returns inside a variable. Now if it does not return anything, we don't need to store anything. Let's do a quick revision. A function that you create consists of three things that you need to write down. The first thing is that prototype, which is basically a way to declare the function. It's a line that ends with a semicolon. It includes the return type, if any, the function name that you define, and two parenthesis with an input between them. If there is funny. Now, if there is no input, you need to write void, and we will cover this in a simulated lesson, the meaning of a void datatype. Now, after writing the prototype, we need the implementation, which is the function body. We use the same line as in the prototype. But instead of ending the line with a semicolon, we end it with two curly braces. This one and this one. Between the double curly braces we arrive the function code. The first step is the function call. Inside our main, we can call our function with its name, function name, and we send two inputs. Now I know that things might not be clear. So let's take an example to make things even more clear. Now, this is a function that we defined and we are going to execute and few seconds. The first part here is called prototype. This is aligned. This is the return type. This function will return an integer. This, the subword is the function name, which is the second part of the prototype, as we already mentioned. Now, we have two parentheses, as you can see here and here. And these two parentheses, we'll end with a semicolon. Now this function will take two inputs. Now it can take more than two inputs depending on our program and our code. But you need to make sure that you have a semicolon between each of these inputs. And you have the type and the name for each of these inputs. So we have the data type for the first input integer, and the name is x comma. Then the data type of the second input is integer. And its name is why? The second thing? Now, this is the first thing that we have. It's called the prototype, as we already mentioned. Now, the second thing is the implementation. This is number two. And as we already mentioned, the first-line is the same. It's a common thing between the prototype and the limitation, except for the semicolon, we have to remove it. And after that, we add two curly braces. And between them we will add our code. Now this is the code that you can reuse, and this is the function name. This is the return data type, and these are the two inputs. This function will subtract x minus y. So we'll create a new variable inside the function. It will equal x minus y, so the result will be inside z. And since this function returns an integer, we need to return the summation value. And we end the land by a semicolon. So this is our code. This block is called implementation, which is the second thing that you must do. This is the first thing. Now the third thing is the function call. Now, as you can see, the function call is simply calling the function with its name. Here we have the function name, we have the two parentheses and the semicolon. But then instead of adding and x and y, we are adding two values to be passed to the value, to the function, sorry. And you need to add the same color. Now, can you pass variables? Yes, you can replace this with x and y, or a and B or whatever you want. But you need to make sure that there are only two inputs. Sense. The function takes only two inputs, and you need to make sure that the variables are integers and have values. Now once you send the values to this function, you can call it, which is the third thing. We call this call or function call. Function call. The function call is basically calling. So it will give 52 instead of x and y. And five will be here to be here five minus two equals three. So Z will equal three and it will return three. Now, when you call the function, will return an integer. So we need to create an integer value of variable, sorry, we call it var to store the value that will be returned by the function. And in this case would be three. So var would equal three. And when we print this, it will print result is three. This will be the output in our console window. And here we call the function, as you can see in this line. Inside the main function. You can call it again and again and again without having to live the whole function. Each time you call it, you just write it once and you can call it, let's say ten times, 20 times, whatever you want. Now to make things even more clear, let's implement this pixel size and our Notepad Plus, Plus. Now, to do this, we will start with the usual thing. We will include stdio.h. Now the first thing that we need to do is add a void, main void, which is our main function. Now, what we will do next is simple. We will add the function prototype. Usually the prototype is everything above the mean. So here, function prototype. So the function will return an integer and it's name will be solved. It will take two inputs, x and y, and we will end it with a semicolon. Now, the second step, this is the first step. The second step is writing the function itself underneath the main, outside them in and underneath it as you can see or below it. We are outside the main here, like three, sorry. Implementation. Now what you need to do is simply copy the whole line here from the prototype, paste it here, but remove the semicolon, as we already mentioned, add two curly braces. Now we need to make sure that this is identical to this, except for the semicolon, you'll have to remove it. Now this function will subtract x minus y, a simple C code. And whenever a functional thing or something, it must contain the word return, it will return this value. Now, let's go to the last step, the call. So let's say we want to call this function, give it 52. Now, if we did this and we executed the code, nothing will happen. This function will subtract five minus three, minus two, so it would equal three and the three value will be floating in the memory. So in order to control or to save the result from this function, we need to store it inside a variable. Let's call it var. And it must be the same data type as the return data type here, here, here, and here. So it returns integer. So we need to receive that return value inside an integer. Now once we have that return value from the function, this is the function call. I've felt. By its name. We can print it out using a print f statement results. The one person does D. Here. We need to add above. That's it. Let's save the code. Let's call it functions. Function this. Now, let's compile it. Gcc, c, e, As you can see, a result equal three. Now, we can play a little bit with this code. You can pass variables instead of constants. Let's say that we want to ask the user to enter two values. So first number, and we will take it with a scan f statement, percentage d. Let's call it first. Now. Let me define two variables. Integer, first number of people on 0, integers, second, number equals 0. Now, this is the second number variable that we want to solve this kind of value on side. Let's call it seconds. So here's the first number. The second number. Now we will call the function, and instead of adding the two constants, we will add the first number and the second number that the user enters. Then we will print out the result. Let's add slash, slash here and another slash n. Now let's call this again, compile it. As you can see in the first number, let's say 10. Second number, let's say for that is alt equals x. As you can see, it was implemented without any issues. So a function call can take constants and tag can take variables as long as these variables out of the same type as the implementation. And the prototype, always make sure that you are using the same type or the same datatype. Or else you might end up with syntax or logical errors. This is how easy it is to create a function, user-defined function. As you can see, this is the first step function prototype. The return data type, the function name, and the two inputs ended with a single. Second step is the implementation, which is the function itself. This is above the mean or below the main. The same as the prototype, but instead of a semicolon, you need to add two curly braces and add your code inside it. The last step is the function call, which is basically calling, just like calling someone, calling a function by its name, passing the two inputs and getting the result that it will return, storing the result in side the end, which is the variable that we want to store the results in. That's it for the functions lesson. If you have any questions, please ask in the Q&A will be more than happy to help. 28. Void Keyword in C: Hello and welcome to this new lesson in which we are going to talk about void keyword. We already mentioned void and we talked about it in more than one lesson. But in this lesson we'll talk about it in more details. The void keyword is used to any function to give the meaning of Nothing. For example, a function that takes void and returns void is in front of you. As you can see, this is the return data type, as we mentioned in the previous lesson, and it's void. Now, it also takes void between the two parentheses. That only goal from this function is to print Mike. Now, this can be changed with anything. But this function will never return any variable or any value and it will not take any input values. So for example, if we need to define a function that takes no arguments, we would fly between the two parentheses, the void keyword, just like in this example, if we need to define a function that does not return any output, we would like. Instead of that return type the keyword void. And this is the void return type. The function can take an odd nor three. Turns out, this is basically the whole meaning of void means nothing. If you saw the word void anywhere, it means that this place will takes nothing or we retails nothing. Now, this is another example. This is our prototype for a function that returns nothing and takes nothing. That's why we have void here and here. Then this function is print by name. Now, as you can see, this is the implementation of this function. We use the same prototype, but we add two curly braces and the semicolon. And inside it we add the print state. Now, the last thing is the coal. And calling a void function is easy. You just call it by its name without writing anything between the two parentheses because it doesn't take any output and without receiving a value from this and storing it into a variable. So to call a function that takes void, then write its name and nothing between the parentheses. Just like in this line. She returns void, like in our example, then don't receive its output in a variable, just call it as it is. Now, let's do this in a practical manner. Let's draw our own void function or list suitably, right, sorry, our own void function. Now let's add the hash include that we are used to. Let's zoom in and STD or edge. Let's save the file and call it. Let's void keyword. See. Now inside here, after using the hash include, we need to call the void main function. Now the main function and we void owl can be and let's add void. This is the syntax that we usually use. Now let's try the prototype here. Void, print name, and void. The filename, as we mentioned is void keyword. Now let's copy that prototype, based it down here, and remove the semicolon, two curly braces and rent f y. Now to call, this is the first step, this is the second step. The third step is calling this function inside the main. So simply call it by its name, print name, and add two parentheses without anything inside them. And it wants to return, I think you save file open containing folder CMD. Let's copy the name gcc and the name of these two. Now aided EXE. And as you can see, it executed this function. This is a function that takes nothing out of the tails is nothing. We call it a void function. This is how easy it is to implement it. So now whenever you see a word for it, it means nothing. Don't input anything wanted to tell. I think that's watching this lesson. If you have any questions about the void function, we are here to help. 29. How to Create a Library in C: Hello and welcome to this new lesson in which we are going to talk about libraries in C. So in order to create a library in C, first, you need to know what is a library. A library is basically a set of functions that do specific actions. And we usually create libraries for sensors for, let's say an LCD display for key bad for reading a temperature value, or, or simply a calculator. So let's say that we want to create a new library and call it a kilometer library. We already mentioned that the library is a set of functions. Now these functions to be used, there are few things that we need to write. We know that each function has three things. That prototype, implementation and the core. Now, in order to create a library, we need to know the number of files that we can include. Basically can include unlimited number of files. But we will only concentrate on two types. This is the first file, and let's call it C or main. That C file. Now you can call it calculator. This is the second file that we need to call, and let's call it calculator h. This one is called a header file, and this one is called source file. Extension for this file is dot c and for this file is dot H stands for header. Now, we need to know what are the things that we will write inside each of these fights. The handout file will include the prototype. Prototype, this thing. So now we are done with this. The C5 will include the implementation. So we are done with this as well. Now, the thing that remains is the coal. The coal is basically something we will do in our main C5, which is the main program file. Now, to do this or to call these functions inside our main file, we need to include our library. So we'll write the word include. But instead of fighting these two signs, we will add the double quotation sign. And the only thing that we need to include the header file. So we'll add calculator, the tailor. This line will allow us to call any function inside source file phi of that calculator library. So if we did this, we wrote this line. This means that we can see any function inside that calculator dot c file, which is the file that we created here. So to wrap things up, this is our library. This library has two things. First, a source file, Let's see. Second is file dot h. Now let's call them Can stands for Calculator. Now, that source file, as we mentioned, will include the function's implementation. While the head-up file will include the function's prototype. Now to call the functions, we need to add the hash include, which is this line. Inside our main. If we added this line, it means that we can see and interact with any function inside the calc dot c, which is the source file, this file or this one. And this is basically how easy it is to create a function in C now or solid to create a library in C. Now, to make things more clear, we will clear that very same thing with the very same name calculator library inside our notepad and see how things will be executed. So let's do this. Let's go to our C compiler. Now this is our main file, so we need to do what we do use running, which is include. And in men void. Once you do that, we need to save it. I'll create a new file. Let's see the numbers to make sure that we have the right numbering for all of our files. We have it at 21. So let's call it 21 C libraries. Now inside it, we need to create domain dot c file. This is our first file. Now we need to create another file and name it can see. And this is the source file. Source file. Here we will write the implementation functions. And we need to create another file, which is the header file. Functions prototype. Just like what we mentioned in our explanation, makes sure that it has the same name as the source file, but ends with h of z. And click Save. Now, the implementation for odd functions, we need to add a function that will sum two numbers, x and y. And we need more than we need for functions actually adds multiplication, division, and subtraction for the calculator to add two numbers, to multiply them, to divide them, to subtract them. Now, this is the header file where we wrote the function prototype. Coby these prototypes to the source file. Best at here, the blessed that semicolon with goo braces. Now, we need to start swiping our codes. As usual. This is nothing new. We are writing the implementation for each of these function. So equals x plus y. Print f. Some results equal percentage d. And we'll add that here. Copy the same blinds here, here and here. Now instead of sum here we need to add multiplication. We need to add division. And here we need to add subtraction. Now we are done with that function's implementation inside the source file. But in order to use the print f, we need to include the standard library. This is the standard library. Now, we finished the prototype, we finished the implementation. We need to call them. So we need to add another hash. Include just like what we mentioned with two double quotation, like calc. Now, this means that our main function now can see the functions created inside the source file. So let's call them. Let's call the add function and add 56. Let's add a slash n here to make sure that they will not be printed on the same line. Okay, go back here. You need to call the add function, the multiplication function, divisional function, the subtraction function. Now, we need to say, I think if you want to include the library that is created by the compiler creators, you can add it between the larger and smaller sites like that. But if the library that you want to include is created by a user, you must add it between two double quotations, as you can see here in this library, was created by us. That's why it's added between double quotations. And this library was created by the compiler, manufacturer or creators. So it is added to an integrator rate or less equal signs. So as you can see, this is a good piece of information that you must keep in mind. Now let's save and let's try compiling our code. So here we need to write GCC main.cc. Now, as you can see, here, we have fewer errors. This is because we tried to compile only that first C5. Now write this as C. C, C, as you can see, it combined without any errors. As we mentioned earlier. Compiled to see files, we need to make sure that we named the files here. Now let's execute a e x e. Now as you can see, some results equals 11, okay? We have a problem with the implementation. So here we'll have plus, we'll have multiplication, division and subtraction. Let's call it again. As you can see, 11300 minus one. That's it. Now, as you can see, our code works just fine without any issues. And we just created our first library and see if you have written everything that I wrote and you created this library, then this is the time that you must clap for yourself because you just created your very first C library. I'm sure that this is a lot to take in from one goal. So you might need to pause the video and go back and watch it again to like understand things. And try to repeat it more than once, then you can go to the implementation and apply the same thing that I did. Let's summarize what we have covered in this lesson. In order to create a C library, we mentioned that you need to create two files. You can create more than two files. It's basically a design approach. But what we will create is a source file and the header file, the source file, another file must have the same name with a different extension. The source file is the header file is dot h. Now, these two files are basically the library and we are creating a calculator library. The source file will include the implementation or functions and limitations. While the header file will include the function's prototype. Now, remaining thing is the coal. In order to call these functions, we need to include the library name. The library header file is the thing that we must include in domains sci fi. So I patch include and add the header file calculator, that edge. Now you must add it between two double quotations because this is a library created by a user, not our compiler related library. Stuff, including you can easily call the functions inside your domain, because once you include this, it means that you have the prototype for all of these functions. Since the header file includes the prototypes, you can call them easily. And this is what we did here. This is the function's implementation inside the source file, the header file calculator, the edge includes the prototype and the goal is inside the main. But before calling, we need to make sure that we are using the hash include calculator that edge. And this is written between two double quotation, not between larger and less than signs. This is a user created library. This is a computer or a compiler related library. That's it for how to create a library and see. 30. Arrays in C: Hello and welcome to this new lesson in which we're going talk about arrays in C. Now, artery is a group of data that holds fixed number or value. All of them are the same type. For example, let's look at this syntax. This is called the array definition. That data type here is interior. It's like defining any variable, usual and define a variable. We write int x equal 0. But in this case, instead of fighting this, we are adding these two brackets. And between them, we will add the array size. This is the size of our array. So this line will do this in our memory. It will create five variables. The name will be array, and you can access them using the index. The number that we write here is called index. The first thing that you need to know is that that account starts from 0. So if it has five here, means five elements, so it's 0 to four. Now, that index always starts from 0. It means that the array has elements from element to element. For, as you can see here, length must be constant value and it cannot be variable. You cannot add variables to five here. You cannot do this and array and add X between the two brackets. This is wrong. It will give you a compiler error. Array. The brackets takes only constant, doesn't take variable. And this is what happens when we execute this line. It will create five variables and we can access them by simply writing a 0. And we will see this in practice in a few minutes. Now. This line creates an array of integer of size five. I love that example here is that the array can be initialized during the time of definition. Using this syntax, you can write array five and the two curly braces here and there, and start filling them up. Now since it's an array of integers, we will add integer values and you must separate them with a coma. As you can see here. The line must end with a semicolon. Now, when you do this, it will create this thing inside our memory. To create array 0, give it a value of one at anyone, give it a value of two array to give it a value of three. Array three, give it a value of four. 3a4, give it a value of five. And this is basically these values. As we already mentioned, we'll start with 01234. This is how easy it is to initialize another way during the definition. Now, there are some special cases when initializing the array with values less than its length. So here we have the length five, and we only added two values. The remaining elements will be initialized with zeros, as you can see here, here and here. So it's like you wrote 12 000. These two are the same. As long as you are not adding the rest of the values, the compiler will autocomplete them with zeros. Now, if you try initializing the array with values more than its length, this will lead to a compilation error. So let's say that this array has five elements. Let's go back and we added another comma and six, another comma and seven. This will most likely give you a compilation error because you are adding seven elements to an array of five elements. So five elements, this must be only five. If you add a seven or six, it will give you a compilation error. These are few of the things that you must keep in mind when dealing with an array. Now, let's talk about accessing array elements. What you need to know here is that all, all array elements can only be accessed on the same statement at initialization. Like in this example. You can access all of the items. And here we accessed all of these items. Now, the point is after the initialization that they can only be accessed element by element. So once, once initialized and you want to add a new value, you must add it using this syntax. You will write the array name, two brackets, the element number, then the equal sign. And then you can add the value. Again, that array index starts from 0. So you need to take this into consideration when you are writing this number. You can use a variable to indicate for the element index. So this can be replaced with a variable, let's say x or like array I. And we can add it inside a for loop. This I can be a valuable, but this is during the, let's say, accessing of array elements, not during the initialization. Now if we tried adding a variable inside the initialization line, like in here, it will give us a compilation error. But you can access array elements using a variable that won't cause an error. Other ways that you can access every element is by scanning a variable directly inside an array element. So the elements are being treated like normal variables. So everyone is basically a variable just like x, y, and any other variable. So you can easily access it by simply writing and the elements. And just in this case it's an array. You can even use them inside the print f function. As you can see here, we are printing element 0 and we add percentage d just like a normal variable. And then instead of adding X or Y, we are adding the array element that we want to print. Now, to make things more clear, we will do this in a practical manner. So let's get started. Hello, and now let's add hash include and N main void. Now let's save this. Let's call it array. Folks will be 22. If I recall. I always see. Now, that's it. Let's start by creating a new array. We already mentioned that you need to write the data type name, brackets array size. So let's create an array, array and make the element number five. Now, there's more than one approach to creating an array. You can twist like that, or you can directly initialize it with values 12345. Or you can simply initialize some of the elements, like 12. As we already mentioned, this will add zeros and the remaining elements. This will add these elements inside our array, and this will not add any element inside of our array. The first piece of information that we didn't mention is that you cannot add a variable here next to the five. This is forbidden and C. Now if we tried adding a variable, let's say x equals Pi. Let's slide compile this. Now let's go to raise it. Now, as you can see. Now it did compile correctly, but we have a problem. Now. This problem, Let's go here and try to print. Let's add some values here into that array that we just created with a variable initializer. Let's print the values inside that array. 0 equal percentage d. And similarly like array 0, array. And we want to print this value. Now go back, try to compile, and you'll see that we have an error. Variable sized object may not be initialized, as you can see, and it's indicating this exists element in our array initializers. As you can see, it's not taking the array elements since we have a variable here. Now the fixed this place, this would five common this line. And it should print the value without any problem. As you can see, our element 0 equal one. And this is the first thing that we need to mention, which is do not add a variable inside the array initialization. Now, the second thing that we need to mention is that if you try to initialize an array, let's combine these two and work on this one. If you try to initialize an array with more than its capacity. So here we'll have five elements and we added seven elements. Now, this will cause an error as well. So GCC, as you can see, excess elements in array initializer, and it's pointing to an amine stamp 67. So it's indicating that these two elements are extra elements and your array size is only five. So to fix this error, you need to remove them and make sure that you only add elements with the same number as inside the two brackets. Now, the last thing that we need to mention is the artery or accessing array elements after the initialization. To access them, you need to rename two brackets and the element that you want to access. If you want to access the first element, that will be elements 0. The second element will be element one. Because we already mentioned that the counter inside the array starts from 0 to less than the maximum value, which is five. So from 0 to four. If we want to access element number three, we need to count 012. So here we need to write two. And this will help us access this element. We can send a new value to element number to here, which is basically the three inside of our array. We can replace it with thin. And this is how you can access and other elements to read the value inside it or to change the value. Now you can also print a value, element, percentage d. And we can add the array name. As usual, we can add any numbers. Let's say that we want to print this value. So 0123, we need to add three here. Now let's comment this line. We don't need it. Now I want to blend two values. Array two, since we change the value and array three. Now let's compile and execute. As you can see, the new value here is ten and the value here is four. We printed values number 23, which is 104. Now if you want to print all of that array elements, you can add these 01234. Like kind of go back, compile and execute. And here we have the one to 10451245. Now, this was a place with 33 words are produced with thin. And this line. Now since we are printing using the very same line, but only one thing is changed, which is the value inside the two brackets. We can replace all of this with a for loop. We can add a for loop. Here we can add n x equals 0. X is less than x plus a plus. Now we can cut this line here. The place this would be x. Now, this is the thing that most people fall for, which is the condition inside the if statement. Should they bought it 654 or lists or equal or less. So in my case, the best thing that I prefer to do when dealing with arrays. Simply adding x is less than the number inside the brackets. So x is less than five. This will help us print all the values inside the array, except for element number five, which is an element that does not exist because we have 01234. So always when dealing with for loops and arrays and lists, and add the number between the two brackets to make sure that you are printing all that Ombudsman side battery. Let's execute this line. As you can see, 12345. Now you can make things even more interesting by adding another percentage d here to indicate that element that you are presenting. So we will add another variable. If we added x here. And trying to combine the codes that someday it will print this array element 0 is one array element, one is to array element to this three. Element three is four are relevant for is five, which is a very interactive way of fronting array elements. Now to make things more convenient, we need to start the elements with one instead of 0. So you can easily do this by adding last 12 between brackets or parentheses. Now, combine and run, as you can see at element 12345, It's more convenient for the end-user to see one. There is nothing called element 0, since he doesn't know that an array starts with 0. So it's more user-friendly to start with one user interface. But you must know deep down that it starts with 0. This is how you can easily print the array element. Now in the next lesson, we will take a good example of how we can take elements into the array and print elements on the display just like this execution. Now the last thing that I need to mention here is maybe some of you are asking why using arrays to begin with, why don't we use variables? Now? We can use variables. You can go and create, let's say five variables. Give them these values. X1, X2, X3, X4, X5. And you can simply print them using five, print f statements. Now that it was basically created, or let's say used in C, to make sure that you don't waste your time by creating a 100 variable of the same datatype. Since we are getting five integer variables, why don't we create the mood single line instead of five lines? Why don't we print them with two lines and instead of printing them with five print f statements. Now this appears more convenient when you are creating an array of 100 elements. Let's say that we wanted to spend a 100 element, not just five elements. It won't be convenient to create a 100 integer variable and keep naming them X1, X2, X3, X4, X5, X6, up to x 9900, and giving them values. The easiest way would be to create an array like this of a 100 elements and to print it using two lines and instead of a 100 print f statement. And this is why Hadley was created. Now if we try to execute this line, you can see that our compiler printed the first five numbers. And as we mentioned earlier, if you haven't added the rest of the numbers, it will automatically add zeros. So here we printed a 100 variable with only two lines using a for loop. This is something you can do with arrays, but you cannot do with the regular integers and regular variables. So you can either go with this approach, you can simply use one line of code to create these five variables. And this is the main point of using to save time to make sure that you get the best results out of your, let's say, data management. And to easily manipulate print, take n values inside your array. That's it for this lesson. 31. Arrays example in C: Hello and welcome to this new lesson in which we are going to take a practical example of how to use an array. So let's get started, right, include a CBIO, delta H and main void. And let's write, let's say the code inside here. 23 example. Let's see. As usual, let's add the filename here. Now let's create another and marks five. Now this is an array that will take five elements and we call it marks. Now we will ask the user to enter his mark using a for loop. So integer x, x is less than five, as we already mentioned, X plus plus. Now scan f will be used the same as with variables percentage d and marks of x. Now to make things more convenient, let's ask the user to enter his mouth and your mouth. Okay, now, let's add another percentage d here to indicate which mark you will be entering. And in here we will add x plus one. Now, this will ask the user to enter, say first Mark, second mark, third Mark. And he will keep entering values. And the for loop will make sure that each new value would be stored inside one of that array elements. We have five elements. Now, the second thing is printing a marks. So we'll copy the same for loop. We will remove the scan f. We will tell him that first mark equals array here. So first mark x plus one. Now this will make sure that we are printing the values that the user gave to us. So he will enter five marks, and we will print these five marks. The first percentage d will be replaced with the mark number, which is 12345. And the second percentage d will be replaced with the market itself. Now, let's compile the code editor. And here you can see it's asking us to enter first mark. So let's write 98 is 706050. Now as you can see, second mark is 83rd, mark is 74th mark is 65 miles is 50. Just like what we entrance here. Now. It did start with two, not 0. So we need to add 0 here and 0 here. And we need to add a percentage d here are solid percentage n. So now let's start again. 9080706050. And here there are 9080706050. Now what if you want to print the average? It will be a very easy thing to do inside this application since we are using arrays. So n sum or average and sum. Now in here, inside the for loop, we will add plus equal, sum plus equal marks of x. So each new value of x that their users entering, we will take the value and add to the sum. Once we are done with this for loop, we will have all the values inside the sum. We can easily go here and write average equals sum divided by five. And we can print the average here. About equal percentage d average. Now let's try this out on your screen. Now, let's run line, line, line, line, line. So as you can see, these are the five marks. And this is the average which is 90, because as you can see, I wrote all of them as night. This is how easy it is to create a program that takes Mars from the user and prints his average without having to create five variables, without having to sum these variables, and without having to use five, scan f statements and five print f statements. So we only did this with a few lines of code. This is, and this is how great arrays are. That's why you should use arrays whenever you feel that you have same datatype for a lot of variables. Just like our marks here or any other type of situation. Again, arrays will make your life much easier. You can do the work without them, but you have to keep copying and pasting lines of codes. Losing memory, and losing time. Thanks for watching this lesson. If you have any questions about any of that line, of course that we wrote here.