Strings are a fundamental data structure of Ruby. Let’s do a quick tour.

Here’s a simple string.

Individual characters are accessed with square brackets. Strings are zero-indexed.

An out-of-bounds access returns nil.

Concatenation of arrays is done with +, which creates a new string.

A string can be appended to, which modifies the original string in place.

Strings can be interpolated. The content of the curly braces is a Ruby expression.

Ruby processes escape sequences in double-quoted strings.

This allows escaping out of interpolation.

Ruby process neither escape sequences nor interpolation in single-quoted strings.

Strings can be written in other ways than with quotes.

%q (short for “quote”) creates a string.

The delimiter can be changed.

%q is equivalent to single quotes, and %Q is equivalent to double quotes.

%{} is equivalent to %Q

Multiline strings can be written using a heredoc. The closing identifier must not be indented.

The closing identifier and content can be kept flush with <<-.

Content indentation can be stripped with <<~.

Heredocs can be single-quoted.