1. Recognize a default argument.
2. Build a method that can take in an optional argument, with a default.

We already know that methods can be defined to accept arguments:

def plus_five(number)
	number + 5
end

Above, we defined a method called plus_five that can accept any number and will return the sum of that number plus 5.

Defining our methods to accept arguments allows us to access specific pieces of information within our methods; it allows us to pass in information to our methods.

What would happen if you called the above method but forgot to pass in a number as an argument?

Drop into IRB, copy and paste the above method definition and then call the method like this:

plus_five

You should see the following error:

ArgumentError: wrong number of arguments (0 for 1)

What if you wanted to avoid this error? What if you wanted to supply your method with a default number to use, in the event that it is called without an argument?

Here's where default arguments come in.

With default arguments, you can specify default values for a method's arguments––values that the method will default to using if the caller doesn't pass them explicitly.

This is done using the assignment operator:

def plus_five(number=10)
	number + 5
end

Now, if you call your plus_five method without any arguments, the method will use the default argument of 10 and return 15.

The second objective of this lab is to build a method called say_hello. This method should accept the argument of a person's name. It then should print "Hello " with the name followed by an exclamation point (don't forget that space after the "Hello"). For instance:

# I call on the method, say_hello, and give it the string "Gabriela" 
say_hello("Gabriela")

# The method prints this text to the screen:
Hello Gabriela!

There is one more thing this method should do: if you call on this method and forget to give it the name of a person, it should just say, "Hello Ruby Programmer!". Use a default argument to accomplish this!

1. Run learn to see where you stand.

• You probably got two NoMethodErrors. This means the test was looking for a method called say_hello but couldn't find it.

2. Define the method in say_hello.rb

• Run learn again. Are you getting a different error? If you haven't seen this error, guess what it's trying to tell you then Google it with the word "ruby".

3. Get all the tests to pass!
4. Once all of the tests are passing, use learn submit to submit your lab. Or alternatively, you can stage and commit your code; push it up to your fork; and submit a pull request.