Until Loops

Quick reference

• 00:04 Okay, in this video, I want to talk about until loops.
• 00:06 The last video, we talked about the while loop,
• 00:08 my terminal finally uncrashed itself.
• 00:10 So until loop is very much like a while loop, but
• 00:12 the logic is a little bit different, and you'll see it looks the same.
• 00:16 It's just until some condition do, and then do something, right?
• 00:21 So it looks very much like a while loop.
• 00:24 But you'll see in just a second when we actually build one of these,
• 00:29 the logic behind it is a little bit different, and sort of useful.
• 00:33 So let's just go ahead and make one of these.
• 00:35 And just like before, I can create, let's create a counter.
• 00:38 I'm just going to call it num, like we called the number in the last video,
• 00:41 doesn't matter, name it whatever you want.
• 00:43 So, until num = 10 do, and let's do the same thing.
• 00:47 Let's put our num, and
• 00:49 then let's now create our increment assignment operator here.
• 00:54 So if we save this and come down here and run it, we get this same 1, 2, 3, 4,
• 00:58 5, 6, 7, 8, 9, 10, and then it stops.
• 01:01 It keeps working until this condition is met.
• 01:04 Let's create a number = 0.
• 01:06 Let's create a while statement, just to look and
• 01:10 sort of see the difference, while number is less than 10, do something.
• 01:18 number += 1.
• 01:24 Here we go, so you can see they look very much alike.
• 01:29 Same sort of formats, same sort of look and feel to them.
• 01:33 But while this is less than 10, do this,
• 01:35 versus do this until this condition gets met.
• 01:39 In both instances, we're trying to meet some sort of condition.
• 01:44 It's just sort of in your brain which way you want to count down to sort of
• 01:48 categorize these things.
• 01:50 And there are specific reasons why you might want to do it
• 01:53 with an until loop versus a while loop, but they're very, very similar.
• 01:56 So really, it's just a personal preference a lot of the time, so
• 01:59 we can play around with this with a little bit of the time here.
• 02:03 Let's say we can go your number is,and then we can do our string interpolation,
• 02:10 use the hashtag, put that in there, save it.
• 02:14 Now if we run this, you see your numbers 1, your numbers 2,
• 02:19 your numbers 3, so all kinds of stuff.
• 02:22 And I should mention, it really doesn't matter what kind of loop you're doing,
• 02:25 we've just got one line of code here.
• 02:27 You can put an entire block of code here.
• 02:30 You can put whatever you want, as many lines as you want.
• 02:32 You can put other loops inside of your loops.
• 02:35 Let's copy this loop here, and let's change this to 5,
• 02:39 just to make it a little less wieldy.
• 02:41 And now inside of this code block, we can paste in our other loop.
• 02:45 I'm just going to tab this over and same thing here.
• 02:47 Let's change this to 3, and instead of puts-ing out a number,
• 02:51 let's puts out I like cheese, because I do.
• 02:54 And remember, we have to increase increment our counter, so let's save this.
• 02:58 Now what's going to happen here is this is our main loop, this top one, and
• 03:02 it's going to run five times.
• 03:04 And every time it runs, it's going to print out I like cheese three times,
• 03:08 because that's what this loop will do.
• 03:10 So it'll go through one time, I Like Cheese!, I Like Cheese!, I Like Cheese!,
• 03:14 loop back around.
• 03:15 Go through it the second time, I Like Cheese!, I Like Cheese!, I Like Cheese!,
• 03:18 I Like Cheese!.
• 03:18 Loop back around the third time, the fourth time, the fifth time,
• 03:21 until this main loop completes.
• 03:23 So let's save this and run it.
• 03:25 If we've done it correctly, we have your number is 1, I like Cheese!,
• 03:27 I like Cheese!, I like Cheese!.
• 03:29 Your number is 2, I like Cheese!, I like Cheese!, I like Cheese!, number is 3,
• 03:32 4 and 5, and on and on.
• 03:33 So just sort of an example to show you that you can put other loops
• 03:36 inside of this code block, but you can put anything in there.
• 03:39 Other conditional statements, any kind of code that you want,
• 03:42 as much as you want, or as little as you want inside of your loop.
• 03:45 So those are until loops.
• 03:47 In the next video, we're going to look at the for and the each loop,
• 03:50 which are both a little bit different.
• 03:52 They have a little bit different format than these last two loops.

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