We're going to make a file that will print "Hello World!" to your terminal.
- Create a new Ruby file.
- Write syntactically valid code to produce "Hello World!"
- Run a Ruby file.
- Run the Learn gem.
- Submit a Learn lab.
Get started by clicking the Open button in Learn.
Creating a File
You will need to create a text file called
hello_world.rb within the lab's directory. The
.rb file extension is a common convention for specifying the language of the file - in this case, Ruby. To create this, in the Learn IDE's terminal type
touch hello_world.rb or use the "Create New" or "New File" option in the Editor. If that worked as expected, you should now see the file appear in the file browser. You can open this file by double clicking on it in the file browser. You should now see an empty file open in your text editor, ready to be edited.
In the file
hello_world.rb that you created, you need to write a single line of code that prints the string Hello World! to your terminal. To print in Ruby, you need to use the method
puts which is short for "output string." And because Hello World! is a string, you need to surround your text with
puts "Hello World!"
Anytime you make changes to a file (like the one you've just made) you need to save the file, so your changes are preserved. If you forget to save the file before you run your tests, the last saved version of the file will be run — without your changes — and this can be very confusing! In this case, if you forget to save, what gets run might be just an empty document (which won't do anything very exciting). Always remember to save the file every time you make changes by selecting Save from the File menu.
Executing Your File
Execute this file by typing
ruby hello_world.rb into your terminal and pressing
ruby part of that command tells your computer to use the Ruby interpreter when reading and executing the code in your file. The second part of the command,
hello_world.rb is the path to the file you want to run.
Note: be sure to save your file before trying to print, otherwise it will not work.
You should see:
$ ruby hello_world.rb Hello World!
Confirm everything is working by running the
learn command. You should see that all tests are passing (e.g. no red error text).
Note: When you write code, the case (uppercase/lowercase) of characters matters, and so your test will not pass unless you print "Hello World!" exactly.
Submitting Your Lab
Submit your solution by typing
learn submit into your terminal, then click Next Lesson to move on.
Your adventure in Ruby has only just begun!
Hello World History
A small piece of coding history—a handwritten version of Hello World in C (an early programming language).
Hello World! by Brian Kernighan, from Artsy's Algorythm Auction based on a 1974 Bell Laboratories internal memorandum by Brian Kernighan, Programming in C: A Tutorial, which contains the first known version.
View Hello World on Learn.co and start learning to code for free.