Ruby Examples: Hello World

#---Hello World---

Our first program will print the classic “hello world” message.

Here’s the full source code:

              puts 'hello world!'
            

To run this, copy this single line code to a new plaintext file. Save the file as “hello.rb” and run it using the ruby command like so from the terminal:
ruby hello.rb.

This should print:
hello world!

Congrats! You’ve run your first ruby program and you did it without importing any library or defining a class or declaring a variable.

The puts method is typically how you’d print something to the standard output.

An empty puts prints an empty line.

You can also use p instead of puts.
It’s shorter and provides extra info that’s useful while debugging:

              puts '42' # => 42
p '42' # => "42"
puts "a\bb" # => b
p "a\bb" # => "a\bb"
            

Both puts and p are ruby methods from the Kernel module which is included by default implicitly in every ruby program.

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