In this one, we explore the concept of looping constructs, visually, in computer programming.
In case you missed it, here are the previous parts of the series
0:00 Okay, so now that we've talked a little bit
0:03 about functions with their arguments
0:05 and also a little bit about functions
0:07 with multiple arguments, this naturally leads us
0:11 to the next thing. What if I want to make that one square
0:16 but I want to make it multiple times?
0:19 Sure, I can copy it and paste this line
0:23 and paste it again, right,
0:26 and then paste it again,
0:28 so and and so forth. So, for example,
0:30 let's try having it pasted twice.
0:33 I'm gonna remove these comments here,
0:36 and just so you remember, this 50 goes in for the length,
0:40 it replaces every part of the length with 50.
0:43 This 90 goes for the angle, it replaces every angle with 90.
0:47 That's how it works, okay.
0:49 So let's go back real quick and simply run this now.
0:54 Okay, so I'm gonna hit the shortcut key to run it.
0:59 And you can see I said draw two squares and it did.
1:03 But, here is the most amazing concept in programming,
1:09 which is the concept of doing things over and over again,
1:12 also known as loops.
1:14 So if I said I want you to do 10 pushups,
1:19 that's like a loop.
1:22 And every time you do a pushup
1:23 I count one, two, three, four.
1:25 And then once you hit 10 I stop automatically.
1:28 So a way to say that here is you can say
1:32 for pushup in range 10.
1:35 So for each pushup for 10 times, do this.
1:40 And this pushup part, I can call it whatever I want.
1:42 I can call it this,
1:44 I can call it I,
1:46 we'll just keep it simple and leave it at one letter I.
1:50 And what we're gonna do is,
1:52 all this part says is run something 10 times, okay.
1:58 That's what that part essentially says.
2:01 If I run that code on the left hand side,
2:03 if I show you what a range of 10 gives me,
2:05 it gives me this.
2:07 So when I do range 10 it won't really show you,
2:10 it kinda hides what it gives you,
2:12 but in reality it gives you a list of 10 numbers, okay.
2:17 So we're gonna talk about more things like lists
2:20 and integers and floating points in our next video.
2:23 But for now, I just want you to think of it
2:26 like it gives us 10 things and so it runs 10 times.
2:30 Okay, so if I did for I in range 10,
2:35 and I said print I,
2:39 what actually happens is the first time in this list,
2:42 the first time you run through in this loop,
2:45 I is zero.
2:46 Then the next time,
2:48 this range 10 is really this list here,
2:52 so I is zero the first time then it's one,
2:55 then it's two, then it's three, then it's four.
2:57 And each time what happens in the loop
2:59 is the part that's indented inside of the loop,
3:02 that's the part that runs over and over and over again.
3:06 So what happens the first time I is zero,
3:08 we say print zero and we get the zero right here.
3:11 Then we say I is one, so I is one over here,
3:14 and then it says print one, we get one over here.
3:18 Then in the last one, I turns out to be nine,
3:21 so we print nine and then we get this nine over here.
3:25 Okay, that's the basic idea of how the loop works.
3:29 So the part that we want to run over and over again,
3:34 we're going to put it inside of this loop.
3:36 Notice the colon at the end, very important.
3:39 And I'm gonna put this part inside of the loop.
3:42 And I don't even need to put that,
3:44 I can just do this
3:48 and I'm basically saying,
3:49 do this thing here, draw a square, four times.
3:53 That's all I'm saying, okay.
3:55 And I will replace this code in that regular way
3:59 without a loop and I'll prove it to you.
4:00 So first let's run it like this.
4:08 Dang, that was cool, right?
4:11 That was really frickin cool.
4:13 It just ran that four times in a row.
4:15 Now, I can show you what I mean, okay,
4:21 and I'm gonna comment out these lines.
4:26 And you can see it's gonna draw that
4:28 same four squares that we just drew, okay, just like that.
4:32 But by using a loop, your code gets a lot more clear.
4:37 What if you didn't want to run it four times?
4:38 What if you wanted to run it one million times, yeah?
4:42 It would be a lot harder to write
4:44 that out one million times,
4:45 but it's really easy to write one million in here.
4:48 I think that's one million.
4:50 That's 10, 100, 1000,
4:54 10,000, 100,000,
4:56 1,000,000. That's actually 10 million.
4:59 So there you go, 10 million.
5:02 So this thing is gonna run 10 million times.
5:05 If I ran it, and I'm gonna close it really quickly
5:08 cause this is gonna keep running forever,
5:10 but you'll notice that it just keeps overlapping
5:13 on the same square and it's gonna do that
5:15 10 million times so if I went to sleep
5:17 and woke up this will probably still be happening
5:20 and then it'll still be happening after that.
5:23 So let's exit that before something crazy happens.
5:29 Okay, so that's loops for you guys.
5:33 That is it for this video,
5:35 I will see you in the next video.