Ruby String Methods

Ruby String Methods
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Ruby has many built in methods to work with strings. Strings in Ruby by default are mutable and can be changed in place or a new string can be returned from a method.

Length:

  • The .length property returns the number of characters in a string including white-space.
"Hello".length
# returns: 5
"Hello World!".length
# returns: 12

Count:

  • The .count method counts how many times a specific character(s) is found in a string.
  • This method is case-sensitive.
"HELLO".count('L')  
# returns: 2
"HELLO WORLD!".count('LO')  
# returns: 1

Insert:

  • The .insert method inserts a string into another string before a given index.
"Hello".insert(3, "hi5")
# returns:
Helhi5lo
# "hi5" is inserted into the string right before the second 'l' which is at index 3

Upcase:

  • The .upcase method transforms all letters in a string to uppercase.
"Hello".upcase
# returns:
HELLO

Downcase:

  • The .downcase method transforms all letters in a string to lowercase.
"Hello".downcase
# returns:
hello

Capitilize:

  • The .capitalize method make the first letter in a string uppercase and the rest of the string lowercase.
"HELLO".capitalize
# returns:
Hello
"HELLO, HOW ARE YOU?".capitalize
# returns:
Hello, how are you?

Note that the first letter is only capitilized if it is at the beginning of the string.

"-HELLO".capitalize
"1HELLO".capitalize
# returns:
-hello
1hello

Reverse:

  • The .reverse method reverses the order of the characters in a string.
"Hello World!".reverse
# returns:
"!dlroW olleH"

Split:

  • The .split takes a strings and splits it into an array, then returns the array.
  • The default method splits the string based on whitespace, unless a different separator is provided (see second example).
"Hello, how are you?".split
# returns:
["Hello,", "how", "are", "you?"]
"H-e-l-l-o".split('-')
# returns:
["H", "e", "l", "l", "o"]

Chop:

  • The .chop method removes the last character of the string.
  • A new string is returned, unless you use the .chop! method which mutates the original string.
"Name".chop
# returns:
Nam
name = "Batman"
name.chop
name == "Batma" # returns false
name = "Batman"
name.chop!
name == "Batma" # returns true

Strip:

  • The .strip method removes the leading and trailing whitespace on strings, including tabs, newlines, and carriage returns (\t, \n, \r).
"  Hello  ".strip
# returns:
Hello

Chomp:

  • The .chomp method removes the last character in a string, only if it’s a carriage return or newline (\r, \n).
  • This method is commonly used with the gets command to remove returns from user input.
"hello\r".chomp
# returns:
hello
"hello\t".chomp
# returns:
hello\t #because tabs and other whitespace remain intact when using `chomp`

To Integer:

  • The .to_i method converts a string to an integer.
"15".to_i
# returns:
15 #integer

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