Ruby different types of strings and heredoc

TLDR

• Ruby has 6 ways to create strings, ', ", %q(), %Q(), %() and HEREDOCs.
• Ruby strings have interpolation as well as escape sequences(\n, \t, etc) handling.
• %Q/%/%q can use any character as delimiter e.g. (, {, etc.

How to use

• Interpolation + escape sequences => "
• Same as above but don’t want to escape using \" => %Q()/%()
• No Interpolation or escape sequences => '
• Same as above but don’t want to escape using \' => %q()
• Multiline large text => HEREDOC. Always use <<~TAGNAME and make life easier.

Types of strings

Double quotes

• Look like "A string".
• Are interpolated.

  a = 3
  puts "a = #{a}" # => "a = 3"
  

• escape sequences.

  a = 3
  b = "\n" # => \n is newline character
  

• Need to escape " within them.

  a = "This is a \"super\" string" # => This is a "super" string
  

%Q() and %()

• Same as double quotes.
• No need to escape ".

  a = %(This is a "super" string) # => This is a "super" string
  

• Can use any delimiter.

  %{a} == %(a) == %[a]
  

Single quotes

• No interpolation or escape sequences.

  a = 3
  puts 'a = #{a}\n' # => "a = #{a}\\n"
  

• Need to escape ' within them.

  a = 'This is a \'super\' string' # => This is a 'super' string
  

%q()

• Just as %Q is to Double quotes, %q is to single quotes.
• Same as single quotes.
• No need to escape '.

  a = %q(This is a 'super' string) # => This is a 'super' string
  

• Can use any delimiter.

  %q{a} == %q(a) == %q[a]
  

HEREDOC

• A way to write multiline strings, or templates in another language.
• Better way to write multiline strings as multiple options are provided.
• Supports interpolation and escape sequences.
• Basic usage

  a = <<HEREDOC
  This
  is
  a
  multiline
  string
  HEREDOC
  

  • Start with <<{TAGNAME in uppercase}.
  • Start string on a newline.
  • End with <<{TAGNAME} on a newline.
• <<-TAGNAME allows us to write the ending tag at any indentation.

  def method
  a = <<-HEREDOC
  This
  is
  a
  multiline
  string
      HEREDOC
  end
  

• <<~TAGNAME removes the starting whitespace from all lines equal to the lowest amount of starting whitespace on any line.

  a = <<~HEREDOC
    A
  B
  C
    D
    HEREDOC
  puts a # => "  A\nB\nC\n  D\n"
  

Summary

There you have it, the basics of using strings in ruby. Here’s the link to the official String docs in case you’re interested.