Variables and Strings

So far your programs have only printed fixed text. Real programs need to remember information and reuse it, and that is exactly what variables are for. A variable is simply a name you choose to store a piece of information so you can use it later.

Creating a variable

In Ruby, you create a variable by picking a name and using a single equals sign to store a value inside it.

name = "Ava"
puts name

Here, name is the variable, and it now holds the string "Ava". Notice that when you print a variable, you do not put quotes around its name.

Variables can change

Variables are called variables because their value can vary, or change, over time.

name = "Ava"
puts name
name = "Sam"
puts name

This program first prints "Ava" and then prints "Sam", because the variable name was updated in between.

Combining text with interpolation

Often you will want to mix a variable into a longer sentence. Ruby makes this easy with a feature called string interpolation. Inside a double-quoted string, you can place #{} around any variable, and Ruby will replace it with its value.

name = "Ava"
puts "Hello, #{name}! Welcome to Ruby."

This prints "Hello, Ava! Welcome to Ruby." Ruby quietly swaps #{name} for whatever is stored in the variable before printing the line.

An important detail about quotes

Interpolation with #{} only works inside double-quoted strings, not single-quoted strings. That is one of the main reasons Ruby programmers reach for double quotes so often.