Strings

Front 1

Escaping quotes in a string

Back 1

"\"Pigs\" is double quoted, and this is a backslash \\"
will print:
"Pigs" is double quoted, and this is a backslash \

Front 2

How to use string interpolation and to prefer it to concatenation.

Back 2

Interpolation
It is very common to build up strings from other strings.

worst_day = "Monday"
"#{worst_day}s are the hardest."
# => "Mondays are the hardest.

Interpolation is usually the idiomatic, clean way to build up strings. Sometimes you'll want more power. Strings have methods that correspond to array's << and + methods: For example:

likes = "race cars, lasers, aeroplanes"
dislikes = "harmonicas"

"I like " + likes + ". I don't like " + dislikes + "."
# => "I like race cars, lasers, aeroplanes. I don't like harmonicas."
You'd probably prefer string interpolation here, but concatenation is an option. And not true: harmonicas are cool.

It is preferred to use the shovel (<<) operator for this; you'll look cooler:

count_in = ""
count_in << "One, "
count_in << "two, "
# ...

Front 3

Accessing a substring

Back 3

"this is my sentence"[5..6]
# => "is"

Front 4

Split a string into parts

Back 4

ice_creams = "Bi-Rite, Humphrey Slocum, Mitchell's"
ice_creams.split(", ")
#=> ["Bi-Rite", "Humphrey Slocum", "Mitchell's"]

motto = "We all scream for ice cream!"
motto.split(" ")
["We", "all", "scream", "for", "ice", "cream!"]

Front 5

Chomp

Back 5

Returns a new String with the given record separator removed from the end of str (if present). If $/ has not been changed from the default Ruby record separator, then chomp also removes carriage return characters (that is it will remove \n, \r, and \r\n).

"hello".chomp #=> "hello"
"hello\n".chomp #=> "hello"
"hello\r\n".chomp #=> "hello"
"hello\n\r".chomp #=> "hello\n"
"hello\r".chomp #=> "hello"
"hello \n there".chomp #=> "hello \n there"
"hello".chomp("llo") #=> "he"

Front 6

Strip

Back 6

Returns a copy of str with leading and trailing whitespace removed.

" hello ".strip #=> "hello"
"\tgoodbye\r\n".strip #=> "goodbye"

Front 7

.to_i

Back 7

"12345".to_i #=> 12345
"99 red balloons".to_i #=> 99
"0a".to_i #=> 0
"0a".to_i(16) #=> 10
"hello".to_i #=> 0
"1100101".to_i(2) #=> 101
"1100101".to_i(8) #=> 294977
"1100101".to_i(10) #=> 1100101
"1100101".to_i(16) #=> 17826049

Front 8

.to_sym

Back 8

"Koala".intern #=> :Koala
s = 'cat'.to_sym #=> :cat
s == :cat #=> true
s = '@cat'.to_sym #=> :@cat
s == :@cat #=> true

Front 9

*

Back 9

Copy—Returns a new String containing integer copies of the receiver.

"Ho! " * 3 #=> "Ho! Ho! Ho! "

Front 10

.each_byte

Back 10

Passes each byte in str to the given block, or returns an enumerator if no block is given.

"hello".each_byte {|c| print c, ' ' }
produces:

104 101 108 108 111

Front 11

gsub

Back 11

Returns a copy of str with the all occurrences of pattern substituted for the second argument. The pattern is typically a Regexp;

result.gsub(Regexp.union(digits_values.keys), digits_values)