Examples

• 13

  Hello World

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  13

  This example assumes Ruby is installed.

  Place the following in a file named hello.rb:

  puts 'Hello World'
  

  From the command line, type the following command to execute the Ruby code from the source file:

  $ ruby hello.rb
  

  This should output:

  Hello World
  

  The output will be immediately displayed to the console. Ruby source files don't need to be compiled before being executed. The Ruby interpreter compiles and executes the Ruby file at runtime.

  edited Oct 20 at 3:12

  

  

  

  
• 11

  Hello World with Shebang (Unix-like operating systems only)

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  11

  You can add an interpreter directive (shebang) to your script. Create a file called hello_world.rb and write the following script:

  #!/usr/bin/env ruby
  # file: hello_world.rb
  
  puts 'Hello World!'
  

  Change the script executable permissions. Now, you do not need to call the Ruby interpreter directly from the command line when you run your script.

  $ chmod u+x hello_world.rb
  $ ./hello_world.rb
  

  edited Nov 3 at 19:49

  

  

  

  
• 7

  Hello World from IRB

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  7

  Alternatively, you can use the Interactive Ruby Shell (IRB) to immediately execute the Ruby statements you previously wrote in the Ruby file.

  Start an IRB session by typing:

  $ irb
  

  Then enter the following command:

  puts "Hello World"
  

  This results in the following console output (including newline):

  Hello World
  

  If you don't want to start a new line, you can use print:

  print "Hello World"
  

  edited Oct 20 at 3:12

  

  

  

  

  
• 4

  Hello World without source files

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  4

  Run the command below in a shell after installing Ruby. This shows how you can execute simple Ruby programs without creating a Ruby file:

  ruby -e 'puts "Hello World"'
  

  You can also feed a Ruby program to the interpreter's standard input. One way to do that is to use a here document in your shell command:

  ruby <<END
  puts "Hello World"
  END
  

  created Jul 21 at 19:10

  
• 3

  Hello World with tk

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  3

  Tk is the standard graphical user interface (GUI) for Ruby. It provides a cross-platform GUI for Ruby programs.

  Example code:

  require "tk"
  TkRoot.new{ title "Hello World!" }
  Tk.mainloop
  

  The result:

  

  Step by Step explanation:

  require "tk"
  

  Load the tk package.

  TkRoot.new{ title "Hello World!" }
  

  Define a widget with the title Hello World

  Tk.mainloop
  

  Start the main loop and display the widget.

  edited 2 days ago

  

  

  

  

  
• 0

  My First Function

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  0

  Overview

  Create a new file named my_first_function.rb

  Place the following code inside the file:

  def hello_world
      puts "Hello world!"
  end
  
  hello_world()
  

  Now, from a command line, execute the following:

  ruby my_first_function.rb
  

  The output should be:

  Hello world!
  

  Explanation

  • def is a keyword that tells us that we're def-ining a method - in this case, hello_world is the name of our method.
  • puts "Hello world!" puts (or pipes to the console) the string Hello world!
  • end is a keyword that signifies we're ending our definition of the hello_world method

  edited Nov 3 at 19:49