methods.md

Methods

If you're not already comfortable with methods, it may be worthwhile to do some research beforehand. This article isn't a bad place to start.

1. Learn how to create a method.
2. Learn the meanings of each of these terms regarding methods:

• Method signature/name
• Parameters
• Arguments (how are parameters and arguments different?)
• Method call
• Return values
• Method body

3. Create a method called hello_world which takes no arguments and which prints Hello, World to the screen. Call this method.
4. Create a method called greeting which takes a single argument (a name) and prints Hello, #{name} to the screen. Call this method with a few different names.
5. Create a method called sum_these_numbers which takes two integers as arguments and prints their sum to the screen.
6. Modify sum_these_numbers (written before) so that instead of printing the sum, it returns the sum back to where the method was called. Print the sum (calculated by the method) to the screen, but don't do that printing inside of the method.
7. Learn the difference between implicit and explicit returns in Ruby. How do you return values without the return keyword?
8. Create a method called is_even, which takes a single integer, and which then returns true if the number is even, and false otherwise.
9. Read about the Single Responsibility Principle. Be able to define it in your own words, preferably in just 1-2 sentences. Recognize that the difference between the two sum_these_numbers methods (created in the previous two steps) is that one calculates the sum and does output, whereas the other just calculates the sum. Which one better adheres to the SRP?
10. Write a method which calls another method, then uses its return value.
11. Learn how to use the yield command (within methods), and then call a method with a block. This is particularly useful for iterators. As you become a better programmer, you'll find that knowing when to use this technique is a matter of intuition and experience, rather than anything very prescribed.
12. Look at problems from the previous steps, particularly ones where the program takes some information, does some stuff, then comes back with a result. Turn a few of these into methods. Almost all of the problems listed in the previous sections can be re-written to use methods and to adhere to the single responsibility principle. Go ahead and use multiple methods if necessary.
13. (Advanced) Do some research into recursive methods (methods which call themselves). Research recursive solutions to the Fibonacci Sequence generator (which you've seen already), and try implementing them. Recursive methods are extremely useful for iterating over certain types of data structures, but they won't be useful to you just yet.