Strings

A string is a piece of text: a sequence of characters in quotes.

Syntax

single = 'Hello'
double = "Hello"

The difference between the two kinds of quotes matters:

• Double quotes support interpolation — #{...} inside the string runs the Ruby code between the braces and inserts the result — and escape sequences such as \n (new line) and \t (tab).
• Single quotes take the text literally; #{...} and \n are left as-is.

Example

name = "Ada"
age = 36

puts "Hello, #{name}!"
puts 'Hello, #{name}!'
puts "Next year you'll be #{age + 1}."
puts "Line one\nLine two"
puts "Hello, " + name
puts "ha" * 3
puts name.length

Expected output

Hello, Ada!
Hello, #{name}!
Next year you'll be 37.
Line one
Line two
Hello, Ada
hahaha
3

Interpolation is the idiomatic way to build strings in Ruby. It also converts values for you — "#{age}" works even though age is a number, whereas "Age: " + age raises a TypeError.

Multi-line strings

A heredoc holds several lines of text. The ~ strips the indentation:

name = "Ada"
message = <<~TEXT
  Dear #{name},
  Thanks for signing up.
TEXT
puts message

Dear Ada,
Thanks for signing up.

Common mistakes

• Using single quotes and wondering why #{name} wasn't replaced.
• Joining a string and a number with +. Use interpolation instead.

Practice

Store a product name and a price in two variables, then print Coffee costs $3.5 using interpolation.

product = "Coffee"
price = 3.5
puts "#{product} costs $#{price}"