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Ruby Methods

A method is a named block of code that does one job. A program defines a method once and calls it by name each time the job is needed.

The same lines copied three times

A class greets three people as they arrive. The greeting takes two lines, and the program copies both lines for each person.

puts "Hello and welcome!"
puts "We are glad you are here."
puts "Hello and welcome!"
puts "We are glad you are here."
puts "Hello and welcome!"
puts "We are glad you are here."

One definition with def and end

The word def starts the method and the word end closes it. The call after end runs the greeting once.

def greet
  puts "Hello and welcome!"
  puts "We are glad you are here."
end

greet

Called by name three times

The definition stays in one place. Three calls print the greeting three times.

def greet
  puts "Hello and welcome!"
  puts "We are glad you are here."
end

greet
greet
greet

Example

def greet
  puts "Hello and welcome!"
  puts "We are glad you are here."
end

def close_doors
  puts "Doors close at six."
end

greet
greet
close_doors

Key points

  • A method wraps one job in a name.
  • Use def to start a method definition.
  • Use end to close a method definition.
  • A method runs only when its name is called.
  • One definition can be called many times.
  • Method names use snake_case, like close_doors.

In this example, the program defines two methods. The greet method prints the two greeting lines. The close_doors method prints one line about the doors. Two greet calls print the greeting twice, and one close_doors call prints the last line.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Programiz Ruby Compiler

Exercise

What does def do in a Ruby program?