There are three main categories of string literals in Ruby: quotation, percentage and heredoc. And every category has its own sub-variants.
Quotation
This category uses single or double quotes to enclose a string.
- Single-quoted strings do NOT allow escape sequences or interpolation.
- double-quoted strings do allow escape sequences and interpolation.
# Single-quoted string
str = 'This is a single-quoted string'
# => "This is a single-quoted string"
# Double-quoted string
str = "This is a double-quoted string with interpolation: #{2 + 2}"
# => "This is a double-quoted string with interpolation: 4"
Percentage:
This category uses the % notation to create different types of string literals.
- Available modifiers are
- Non-interpolable
- interpolable
- array of strings
- array of symbols
- regular expression
- symbol
- backtick
- You can use any non-alphanumeric character as a delimiter, such as parentheses, brackets, braces, etc.
# Non-interpolable string
str = %q(This is a single-quoted string)
# => "This is a single-quoted string"
# Interpolable string
str = %Q(This is a double-quoted string with interpolation: #{2 + 2})
# => "This is a double-quoted string with interpolation: 4"
# Array of strings
arr = %w(one two three)
# => ["one", "two", "three"]
# Array of symbols
arr = %i(one two three)
# => [:one, :two, :three]
# Regular expression
reg = %r(\d+)
# => /\d+/
# Symbol
sym = %s(hello)
# => :hello
# Backtick
cmd = %x(date)
# => "Wed Dec 27 04:07:07 UTC 2023\n"
Heredoc
This category allows you to create multi-line strings.
- You can a delimiter of your choice, such as
EOS,END, etc. - You can use single quotation in the delimiter
'EOF'to disable interpolation in heredoc. - You can use
<<~to remove leading whitespace from each line, or<<-to allow an indented closing delimiter. - You can call a method on a heredoc by placing it after the opening identifier.
- Opening multiple heredocs on the same line is possible by using different identifiers and delimiters.
# Heredoc syntax
str = <<EOS
This is a multi-line string
with heredoc syntax.
EOS
# => "This is a multi-line string\nwith heredoc syntax.\n"
# Heredoc without interpolation
name = "John"
str = <<-'HEREDOC'
My name is #{name}.
HEREDOC
# => "My name is #{name}.\n"
# Heredoc syntax with leading whitespace removed
str = <<~END
This is another multi-line string
with leading whitespace removed.
END
# => "This is another multi-line string\nwith leading whitespace removed.\n"
# Heredoc syntax with an indented closing delimiter
str = <<-TEXT
This is a multi-line string
with an indented closing delimiter.
TEXT
# => "This is a multi-line string\nwith an indented closing delimiter.\n"
# Heredoc syntax with a method call
str = <<-TEXT.chomp
This is a multi-line string
with a method call.
TEXT
# => "This is a multi-line string\nwith a method call."
# Multiple heredoc syntax
puts (<<-ONE, <<-TWO)
content for heredoc one
ONE
content for heredoc two
TWO
# => "content for heredoc one\ncontent for heredoc two"
Top comments (0)