While Loops

Quick reference

• 00:04 In this video, we're going to start to talk about loops,
• 00:07 specifically while loops.
• 00:08 And now, loops are just incredibly important to all computer programming.
• 00:12 It doesn't matter what programming language you're using.
• 00:15 You're always gonna use loops.
• 00:16 They are probably just as important as if else statements, and
• 00:19 that you're gonna use them all the time.
• 00:20 There's a couple of different loops we're gonna look at.
• 00:22 We're gonna look at the while loop and for loop.
• 00:24 In this video, we're gonna focus on the while loop.
• 00:25 The difference between the two is sort of trivial, and
• 00:28 in many instances, you can use any kind of loop you want but
• 00:31 I find that programmers tend to gravitate towards a certain loop.
• 00:35 Me personally, I like to use while loop so I tend to use them all the time.
• 00:39 I could easily use a for loop, instead of a while loop, it's just
• 00:42 a personal preference, so you'll find the one that you like to use the most and
• 00:45 that's the one you'll use for most circumstances.
• 00:48 Now there are some times when you just have to use a while loop or a for loop or
• 00:51 whatever, but it's not all that rare.
• 00:52 So anyway, a while loop looks like, while condition do something.
• 01:01 Now, this looks an awful lot like an if statement.
• 01:03 And in fact, if we change the word while to if, we would have an if statement.
• 01:07 So if you know how to use an if statement, you're already sort of familiar with this.
• 01:10 That's probably why I like to use the while loop, it's just familiar.
• 01:13 So here, we can use our comparison operators.
• 01:16 We can do all kinds of stuff.
• 01:18 And in fact, let's just create one.
• 01:19 So to use a while loop, first we have to set a counter.
• 01:22 And I'm just gonna call it x.
• 01:23 I'm gonna set it equal to zero.
• 01:25 And I'm gonna say while x is less than ten, while this is true, do something.
• 01:31 And let's echo out, your number is x.
• 01:37 And I'm gonna put a line break here.
• 01:38 So it put this on, it's online, okay.
• 01:41 We also need to increment our variable, and to do that,
• 01:44 we use our increment operator that we already learned, and that's just x++.
• 01:49 Now, why do we need to do that?
• 01:51 Well, what happens is, this executes and it checks this condition.
• 01:55 As long as this is true, it'll do this next line.
• 01:57 If we didn't have this here, x would stay zero forever.
• 02:01 And it would loop back round, and it would say zero is less than ten.
• 02:05 It would echo this out.
• 02:06 It would loop back around, zero is less than ten.
• 02:09 Echo loop, zero less than ten, echo loop.
• 02:11 And you get what's called an infinite loop.
• 02:13 It would just keep going forever and ever and ever.
• 02:15 And when we print out, your number is zero a zillion times on the screen, and
• 02:19 your program would crash.
• 02:20 To this day, I forget to do my increment operator on here every now and then, and
• 02:25 my programs crash.
• 02:26 It's just one of the pitfalls of using the while loop.
• 02:29 But it's gonna happen to you, don't worry about it.
• 02:32 It's not a big deal.
• 02:32 You just restart your program and you go I forgot my increment operator.
• 02:36 So let's save this, come up here, and hit reload and
• 02:39 we can just see your number is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
• 02:42 And then it stops.
• 02:43 Why does it do that?
• 02:44 Once it hits 9, 9 is less than 10, so it prints out your number is 9.
• 02:49 Then it increments, and the 9 becomes 10 and then we loop again and
• 02:54 10 is not less than 10, so the whole thing stops.
• 02:57 This thing continues to loop while this is true, but
• 03:00 10 is less than 10 that's false so the whole things stops.
• 03:04 So that's pretty much it, that's a while loop.
• 03:06 There are some variations on the while loop specifically the do while loop,
• 03:11 and you can look up how to do a do while loop.
• 03:13 I've never actually used one.
• 03:15 This while loop will get you through most of a looping that you'll ever need to do.
• 03:18 In the next video, we're gonna talk about for loops.
• 03:21 It's very similar to a while loop, just slightly different and
• 03:24 you'll see all about that in the next video.

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