hello-world.md

Hello World

A "Hello World" program is the first program that most programmers create to explore a new programming language. Be sure to read the wikipedia article which provides even more context about what this is and why we use it!

irb

In the previous lesson, we saw what IRB is and how to execute a basic command in IRB. We can use IRB as our first attempt in creating a "Hello World" program.

1. Open terminal
2. Start IRB by typing irb in the terminal
3. Write an expression which will output the worlds "hello world" to the user:
   puts "hello world"

Ruby file

Now that we see how to write the "Hello World" program using IRB, we can write a ruby program to do the same thing. Let's create a Ruby file and execute that Ruby file instead of doing this directly in IRB.

The advantage of using a Ruby file instead of IRB is that you will have a record of the code that was written so it can be executed again later.

Create a Ruby File

From your ada jumpstart folder in the terminal, run the command which will create a new file:
touch hello-world.rb

Edit the Ruby File

From the terminal, Open your text editor with the current folder's files:
atom .

Edit the hello-world.rb file to add the puts statement:
puts "hello world"

Save the file!

Run the code

From the terminal, Run your code:
ruby hello-world.rb

See the output? Great!