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In this video, we'll write our very first program.

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So what we want to do is we want to create a project.

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So again, I'm in the section 4 workspace, and I'm going to right click on there

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and say new, new project.

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I'm going to select my default template again.

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And I'm just going to call this first program.

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And I'll select next and finish.

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Now notice that project1 is the active project so I want to be sure that

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first program is the active project. So I could just double click on, it

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and I can open up that c++ file. That's it.

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So this is the source code for the first program.

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Now what I want to do is I want to erase this and I want you to really just type it in

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that way you get used to typing these things in at the beginning that's probably the

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best way to do it is just to follow along.

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So let me tell you what this program is about.

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This program is going to ask the user

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to enter their favorite number, a number between 1 and a 100.

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And then it's going to display.

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Wow, that's amazing. That's my favorite number too. That's it. Okay.

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So let's start. First thing we need to do is we need to do pound include

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of iostream.

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Now as I type, I'm going to press io then when I press s,

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you can see that the code completion is helping me out is trying to figure out what I want.

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And it's giving me its guess as to what I want.

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And I want iostream, so I'm just going to select it and close it.

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There is no semicolon here on this statement.

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These pound directives, and we'll talk more about what these preprocessor directives are

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in section 5, but they don't take semicolons at the end.

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So I'm going to press enter. And now we want to create our main function.

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Remember, the main function is the main entry point.

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This is the place where execution begins.

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So we're going to say int main left paren, right paren.

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And then we're going to put a left curly

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and the IDE will terminate that left curly with the right curly.

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We'll talk more about style as we go, but

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some programmers like to line up their braces like this,

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others like to line them up like that.

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Right now, it doesn't matter. Let's just line them up like this.

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All right. So what do we need to do. We need to prompt the user to enter

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their favorite number. So how do I do that? I do that with a cout statement.

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So I'm going to say std::

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cout,

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and we'll do the insertion operator which inserts something into that stream.

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Remember, cout is typically tied to your console, your terminal,

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so the user can type things in.

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And we're going to display,

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enter your favorite

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number between,

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let's say, 1 and 100.

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And I'll just put a colon there.

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Now you'll notice that you've got a quote mark

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and then a terminating quote mark. This is called a string.

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This is called the string literal.

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This will be displayed exactly as is.

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Now this is a statement, so all statements end in a semicolon.

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Remember, main returns an integer

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and that integer is 0 if everything is good. So I'm going to return 0,

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right. So if i run this program now, it's all -- it's going to say is enter your favorite number

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between 100.

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That's it. It's not going to grab the number from anywhere,

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it's not going to display anything else.

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We need to somehow read what the user types in on the keyboard.

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So just like cout,

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writes to the console cin reads from the console.

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So what we're going to do here is we're going to say std

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cm,

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and now we're going to use the extraction operator because we want to extract information.

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And it's the same as the insertion operator except going the other way.

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But now what we're saying is we want to grab whatever the user types in and we want to store it somewhere.

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We where do we store that?

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Well, this is where variables come in. And we'll do

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a lot of talking about variables in section 6.

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I'll talk about how do you declare them, how you initialize them,

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the rules for naming them and so forth.

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But declaring variables is very straightforward. So let's do that here.

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What we do is we tell the compiler. Remember, the compiler is really dumb.

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It's not guessing it. It does exactly what we tell it to do.

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So what I'm going to do is I'm going to tell it that I want a variable name

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and that name is called favorite number that's where I want you to store what the user typed in.

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And you also have to tell it what kind of data that is.

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Is it a string? Is it some big huge structure?

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No, in this case it's just a whole number an integer.

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So we're going to say int

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favorite_number

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;

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that's it. That's a variable declaration.

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You've just told the compiler that this variable name right here favorite number is an integer.

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Now I can read

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information into that, so I can say std::

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and again the std will explain later on, it's a namespace

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but we definitely need it here stdcn

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into favorite number.

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Now again, I'm going to type fav

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and the code completion will try to figure out what I want,

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so it's going to use favorite number I can just press enter

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semicolon on the end.

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So notice what we've done so far, we've included iostream.

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Why did we include iostream because we need the input output libraries.

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We can't do IO without it. So we're including it.

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Now the compiler understands

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about input and output. It understands cout and cin.

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They are defined in here.

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Great, so I'm outputting enter your favorite number between 1 and 100.

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Now the user is going to type something at the keyboard.

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And whatever they type, we're going to store it into favorite number,

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this guy right there.

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Right now we just need to say

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cout

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and I can say something like amazing.

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That's my favorite number too.

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Here we can do an end line, so we

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flush the buffers and print out to the next line.

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That's it. So let's go through this again one more time.

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We've got a main function. This is the entry point. This is where execution begins.

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All c++ programs must have a main function.

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All c++ programs must only have exactly one main function.

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So when the program begins to execute, this is where it starts.

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Here I've defined a variable called favorite number

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and it's an integer, it can only hold whole numbers.

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I'm outputting to the console.

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Enter your favorite number between 1 and 100,

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the user is not going to input something into the console a number.

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And I'm going to read it and store it into that location into that variable, into that box.

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Then I'm going to say cout, amazing. That's my favorite number too.

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And I'm just going to print end line at the end that'll flush out the buffers

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and move the cursor over to the next line.

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Finally, I return zero.

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Everything's good.

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Now next thing to do is to build this program.

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Program is not going to run up by itself. We need to compile it. We need to link it.

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And then we need to execute it. That whole process of compiling

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and linking is called building.

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Now you'll notice that when you right click

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on that source file right here main cpp,

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you see it says compile.

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Now if I press that,

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it's going to compile our program.

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And you can see here 0 errors, 0 warnings.

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We'll talk about what happens if you get errors and warnings a little bit later.

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Also notice that we're using the c++14 standard,

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which is what we want to use.

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That's what we did when we set up that default template if you recall.

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What we need to do next is to build

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the project by compiling and linking

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that's going to create the exe file on windows

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or the executable files on Linux and mac.

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And we'll do that in the next video.