Escape Sequences

Sometimes, we need characters in a string that are hard to 0:00 represent in program code. 0:02 The first line of code prints a string that includes a newline character. 0:05 But it's awkward to read, 0:08 with the second half of the string starting on the second line. 0:10 We want line 3 to include a tab character to indent some text, but 0:14 when I press the tab key, my editor inserted space characters, instead. 0:18 And line 4 isn't even valid Ruby code. 0:22 It's supposed to be a single string that contains double quote marks. 0:25 But what we wind up with is a string containing he said, some invalid Ruby code 0:28 referring to a non-existent object named Whoa, and a second string, which is empty. 0:34 To address this problem, Ruby offers escape sequences. 0:41 An escape sequence is a portion of a string that represents a character that 0:46 would normally be hard to represent in program code. 0:50 Each of these two character combinations you see here 0:53 actually represents a single character. 0:56 So \ followed by n, represents a new line character, which skips to a new line. 0:59 \ followed by t, represents a tab character, which indents text. 1:05 \ followed by a " character inserts double quotes, even into a double quoted string. 1:10 \ followed by a ' character inserts single quotes, 1:16 again, even into a single quoted string. 1:20 And because you're going to need a way to insert backslash characters without Ruby 1:22 thinking you're starting an escape sequence, 1:26 \\ inserts a single backslash character. 1:28 Let's update the previous program to use escape sequences for 1:33 the hard to represent characters. 1:37 So first, let's take the new line character that's in the middle of this 1:39 first line and replace it with \n to represent an actual new line character. 1:42 Let's take the two spaces here on the second line and replace it 1:48 with \t which represents a tab character, that should indent the text for us. 1:51 And let's take the double quote characters that Ruby is mistaking for 1:57 the end of a string, and escape those using backslashes as well. 2:00 So that all of this becomes a single string. 2:04 Let's save that, and try rerunning it. 2:07 And everything works. 2:12 Our \n here on the first line, 2:13 gets replaced with a new line character down below. 2:16 \t gets replaced with a tab character. 2:18 And our \" get replaced with actual quotation marks. 2:22 Just so you know, you don't always have to escape quotation marks into your strings. 2:28 Double quoted strings can hold single quotes without escaping them. 2:33 Single quoted strings can hold double quotes without escaping them. 2:36 But, double quote characters within double quoted strings need to be escaped. 2:40 And so do single quotes within single quoted strings. 2:44 So, now that we know about escape sequences, 2:48 we know that the \n at the end of our answer variable is a new line character. 2:50 When the user presses the enter key to signal they're finished entering 2:56 an answer, it adds a new line character on the end of the string, 2:59 which gets returned by gets. 3:03 To remove it, we'll need to call a method on the string object, 3:06 which we'll learn how to do in the next stage. 3:09 Knowing how to work with strings is another essential programming skill, 3:12 one that's definitely worth practicing. 3:15 Be sure to check the teacher's notes to learn ways to get more practice with 3:17 strings. 3:21 Now you've learned the basics of working with strings in Ruby. 3:22 You can append strings to other strings by concatenating them. 3:25 You can embed data within strings using interpolation. 3:29 And you can embed special characters using escape sequences. 3:32 But that's only a small fraction of the features Ruby offers for 3:37 working with strings. 3:40 To do more, you're going to need to know how to call methods directly on 3:41 the strings, and not just for strings. 3:45 Virtually everything in Ruby has methods you can call on it. 3:48 We'll learn how to do that in the next stage. 3:51