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(upbeat music)

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(keyboard typing)

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-: [Frank Mitropoulos] Hello, everyone.

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In this video, we'll set up Visual Studio Code

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to debug C++ programs.

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We've already set up IntelliSense

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and we've set up a build task.

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So, now we're gonna set up the debug.

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Where do we start?

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It's really quite simple.

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Select one of your C++ files, it doesn't matter which one.

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And then, come up here to run and add configuration.

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Now, you're gonna be asked for your environment,

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select C++ GDB/LLDB, and then the C++ compiler again,

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which in our case is G++.

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Now, you're gonna have some stuff happen

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and things are gonna be changing colors and so forth.

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Don't worry about any of that.

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What we're gonna do now is modify this file

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that was just created called launch.json.

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And we're gonna make one minor change to it.

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Let me close this window up so we can see it.

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What we're going to do is we're going to change

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the entry for cwd.

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It's on line 14 on my system here,

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and we're gonna change this from workspace folder

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to file your name.

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So, I'm just gonna copy that and paste it in here.

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And that's all we're gonna do.

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Now, I'm gonna save this and I'm going to close it

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since we don't need it any longer.

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All right, let's debug our first program.

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Let's modify project two's main CPP file, just a little

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so we have a little information to see in the debugger.

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So, what I'm going to do here, I'm going to add an integer

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and let's just call this my favorite number

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and I'm gonna initialize it to, let's say a hundred,

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just so we have something to look at.

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So, it's still going to display hello from project two,

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but now we want it to prompt the user

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to enter their favorite number.

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So, we'll put another display statement in here

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and we'll just say, enter your favorite number,

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and then we'll read in what they type.

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And we're gonna read that into favorite number.

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And then, finally, we're gonna display

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your favorite number is, and we'll display

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what they typed in right back at them.

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So, we'll say your favorite number is,

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and we'll display what they entered.

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Fave number, followed by a new line.

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All right, so that's it.

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So, we made a small change, but an important change

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because we wanna be able to see

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that favorite number change in the debugger.

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All right, so how do we debug now?

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Select the program you want to debug, again,

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very important that we select that CPP file

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that we want to debug.

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In this case, this is the one we want to debug.

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What we can do now is we can click that bug icon

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right there where it says, run a debug,

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and nothing will happen right away.

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What we need to do is we need

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to set a break point in our code.

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This is where the debugger is going to stop

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when it starts to debug our code.

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So, I want it to stop right there, right on line five.

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So, you could just move along here

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and just select the break points.

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Just click and it turns red and you can select

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as many break points as you want.

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Notice now that the break points show up here.

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There is a glitch in Visual Studio Code

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where sometimes when you have multiple breakpoints

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across different projects, they all show here.

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And what I'd recommend you do is just when you're about

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to start debugging, click on that X right there.

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That erases all the break points from everywhere.

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Now, you don't see any down here,

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and then, you could just come up to your project

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and put the break point exactly where you want it.

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So, now that we've done that,

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we can click on this little green run icon right up here.

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And when I do that, the debugger will engage.

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You can see that there's a build happening

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and now this bottom bar turns orange

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and now there's a couple of things that have just happened.

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Notice that this line five is highlighted

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and the playhead is right there, right on line five.

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That tells you that the debugger stopped at line five,

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just like you asked it to.

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That's where you put the break point.

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So, line five has not been executed, line four has.

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Notice that line four is our declaration of favorite number.

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And if you look over here in your local variables,

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there, you see its value.

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That's pretty cool.

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So, you can see favorite number is a hundred.

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You can also hover over favorite number.

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You'll see the hundred pop up.

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You can do that anywhere it occurs.

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Now, what we want to do is we want

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to execute one line at a time.

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And we can do that with this button right here.

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You can see we've got a series of buttons here

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that allow us to interact with the debugger.

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This steps over the code, this steps into code.

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And I discuss these in more detail throughout the course.

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Here we can just stop the debugger

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and here we can just continue.

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So, what I wanna do is I want to execute one line at a time.

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So, I'm going to select step over.

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And you can see the playhead now moves to line six

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and line five executed and displayed

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something on the screen just like we expected.

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All right, and now it's gonna,

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it's asking you what's your favorite number.

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So, I'm just gonna type in something

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other than a hundred so you can see it change.

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Let's just type in 45, and I'll press enter

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and notice my local variable right here, 45.

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That's pretty neat.

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This allows me to step through my code

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and see what's happening.

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Maybe I made a mistake somewhere,

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it's much easier to see it this way.

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And then, we could just continue writing

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the program and we're done.

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So, you see hello from project two,

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enter your favorite number.

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I entered 45, and then it displayed

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your favorite number is 45, just as we expected.

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When you're done debugging, you can click over here,

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go back to explore, and just debug

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or code whatever project you like.

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All right, so that shows you how to set up debugging.

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So, at this point we've got building, we've got running,

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and we've got debugging all set up.

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In the next video, I'm gonna show you

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how to use Visual Studio Code with the source code

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that I provide for the course.