Let’s build a simple calculator to help!
Ruby arguments represent values that are passed into methods when the methods are run. They allow objects like strings, integers, arrays and hashes to be given to the method so that the method can operate with them. Arguments also make methods flexible — they allow a method to be run with different values that are always operated on in the same way.
A great example is a calculator method.
Basic addition calculator
Let’s say you want a method that will act as an addition calculator. It will add together any two numbers that you give it and return the sum. The two numbers that will be added will be passed into the method via arguments.
def add(number1, number2)
number1 + number2
end
In the code above, the add method accepts two arguments: number1 and number2. Those arguments represent the numbers that add will be called with. Inside the method, the arguments are added together, and the method will return their sum.
Here’s how this method can be used:
add(1, 2)
=> 3
add(3,5)
=> 8
add(10,20)
=>30
add(250, 250)
=>500
In the code above, the add method is run four times, each time with different numbers. When we defined the method, we told add to expect to be given two numbers to operate on by giving it the number1 and number2 arguments. Those arguments were placeholders for the numbers that add would be given when it ran.
Try it yourself
In your terminal, enter irb to start a new Interactive Ruby session, which will allow you to test out and play around with Ruby.
Enter in our method definition:
def add(number1, number2)
number1 + number2
end
Now, run the add method to see what the sum of 237 and 916 is. (Hint: If you’re not sure how to run the method and get that sum, check out the examples above.)
Run the method again, this time passing in any two numbers that you’d like. As you can see, the method will return a different value each time, because its return value is entirely based on the arguments that you give it.
When you’re done, you can run exit to end the IRB session.