For and Each Loops

Quick reference

• 00:00 In this video, I want to look at for loop and an each loop.
• 00:07 And these are,
• 00:08 pretty dramatically different than the last two loops that we used.
• 00:11 So a for loop will start there.
• 00:13 A for loop, it runs a specific number of times over a range of numbers.
• 00:17 And the best way for me to explain it, is to just show it to you.
• 00:20 So we go, for and
• 00:22 let's go number, it's just a variable in, and now we set a range.
• 00:27 So from 0, let's say 2, 5, and that dot, dot just means a range from 0 to 5.
• 00:34 So then we have an end, and inside of here, it does whatever we want it to do,
• 00:39 whatever our code block happens to be.
• 00:41 So let's just put some number, so if we save this, you'll notice,
• 00:45 before we declared we went like number = 0.
• 00:50 We don't have to do that here.
• 00:51 And if we save it, four designates this on its own, so use it in this range.
• 00:58 So from 0 to 5 number starts with 0 and it goes to 5,
• 01:02 befor it slaps these numbers right here into the variable.
• 01:07 So we see 0, 1, 2, 3, 4, 5, we could put something weird like,
• 01:13 I love cheese, right?
• 01:15 So if we save this, and run it, it just prints out,
• 01:20 I love cheese, 1, 2, 3, 4, 5, 6 times.
• 01:23 So 0, 1, 2, 3, 4, 5, that's 6 things, so that's a for loop, kind of weird, right?
• 01:29 But there's definitely reasons why you might want to use that, and
• 01:32 we'll see those later on.
• 01:33 So now, I want to talk about the each loop.
• 01:34 The each loop is equally kind of different than the first two loops
• 01:38 that we looked at.
• 01:39 And the format of an each loop is something.each,
• 01:44 and then do, and then we have this variable.
• 01:50 And then here's our code, whatever we want to do, and then end.
• 01:53 So this is the format, so this looks kind of weird, right?
• 01:56 But it's actually very useful.
• 01:57 So let's just go ahead and make one of these things.
• 01:59 Let's create a range like we did before from 0 to 5,
• 02:03 and we can say, .each for each item in this range.
• 02:08 So for 0, do this for 1, do this for 2, do this, all the way up to 5. do.
• 02:14 And then let's create a variable, and let's just call num, and
• 02:17 let's just puts num, and then end.
• 02:21 So remember for a for loop we didn't have to declare what num was it sort of did it for
• 02:26 us here.
• 02:27 We sort of have to declare it and we just do it like that.
• 02:29 So for save this and run it, we get 0, 1, 2, 3, 4, 5.
• 02:33 Likewise, we can do the same, I love cheese, because I really do.
• 02:38 And it just does I love cheese five times.
• 02:41 So this seems a little bit weird but let's really quickly,
• 02:47 Create an array with John, Tim, and Mary.
• 02:53 So now we can use instead of this range of numbers we can say, for
• 02:58 each item in the names array do this.
• 03:02 So what do you think this is going to do?
• 03:05 It's going to say, I Love Cheese three times because we have three
• 03:09 items in our array.
• 03:10 We could also print out our array, we can go puts num.
• 03:15 Now we run this we get John, Tim, and Mary.
• 03:17 So lots of ways to loop through an array but man, this is very simple.
• 03:22 And that's the each loop.
• 03:22 So, for loop ,each loop, while loop,
• 03:25 until loop you have four solid loops to choose from for different reasons.
• 03:29 You could loop through an array with a while loop just as easily.
• 03:31 So I'll leave that to you to sort of work your way through that.
• 03:34 In the next video we're going to look at FizzBuzz.

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