Blocks in the Wild: Strings and Integers

[SOUND] Ruby makes heavy use of blocks in 0:00 the built in types and the standard library. 0:04 We've encountered some block methods before but now that we know more about 0:10 blocks let's take a fresh look at some of the built in types using workspaces. 0:14 So now that we know more about blocks, let's go ahead and 0:20 take a look at some of the methods that take blocks from classes that we've 0:23 seen in the Ruby standard library. 0:28 First, let's go ahead and take a look at Strings. 0:33 Here is the documentation for the string class. 0:36 And if we scroll down here on the left, let's go ahead and 0:40 look at this each_char method. 0:43 Now when we look at the documentation for something that takes a block, or 0:46 any method really, we can see that it will show you what arguments the method takes. 0:50 Now when we look at this we can see that this takes a block with one argument. 0:56 The block is here and 1:02 this arrow means that it returns a string. 1:05 So let's go ahead and open up our workspace, and I've already launched one. 1:10 I've got it inside of IRB. 1:15 So let's go ahead and take a string here and we'll just say it's a string. 1:18 And we'll set it to Treehouse, and 1:21 let's go ahead and practice that each char method. 1:25 Let's say sting.each_char, and then we send in the block. 1:27 We know it takes one argument, we're just gonna call it c, and 1:32 let's print that out, with a dash right after it. 1:37 So now we can see that this prints out Treehouse, each character of the string 1:45 and it returns a string itself which happens to be the original string. 1:51 Now that's useful because we can do something after that. 1:58 We can kinda chain these methods if we want to. 2:02 And this doesn't really have anything to do with the block, it's just kinda cool. 2:04 We could call upcase on that and then we can see that the actual return is 2:08 TREEHOUSE which is the rightmost method that's called. 2:12 Now let's go ahead and look at another method here. 2:17 In addition to each_char, let's look at each_line. 2:20 This is another method that takes a block and 2:24 lines are separated by a new line character. 2:27 So let's go ahead and test that out in IRB. 2:31 So let's go ahead and create multi-line string here. 2:33 I'm just gonna call it haiku. 2:36 And we're gonna use the here doc format to create the string. 2:39 So, here we have our multiline string. 2:55 And then just to demonstrate the each_line method, we can call each_line. 2:58 And we remember from the documentation, it takes a block with one argument. 3:04 And let's go ahead and just print that out with an asterisk in front of it. 3:09 And now we can see our multi-line string was printed out with an asterisk in front 3:16 of it, just like we expect. 3:20 And then just like the each)char method, a string is returned. 3:22 So, I'm gonna clear my screen here. 3:29 And then the next method that we're gonna take a look at is on Integer. 3:30 And this is a neat one. 3:37 We can take any number and use this downto method, well, any integer. 3:38 And this takes one argument to the method itself. 3:44 And it takes a block also with one argument. 3:50 They have an example here in the documentation, which is 5.downto(1). 3:55 Here's a number, print the number, and then two dots. 3:59 And that will produce this output. 4:04 Let's go ahead and see if we can recreate something like that. 4:06 We can say 5.downto(3) and we'll call that number. 4:10 And let's go ahead and just print the number. 4:17 That should print out the numbers five, four, and three right after each other. 4:21 There we go. And 4:26 then we'll notice here this also returns the original integer that we send in. 4:27 Now numbers are different, we can't do something like (5.1).downto(3), 4:33 because the floating point numbers don't have the downto method. 4:41 And then something else to note when you're working with blocks, 4:48 it's not necessary to put all these spaces here, 4:51 that's just the style that I'm using to make it easier to see 4:54