Question

a = [2,4,5]
a.count-1 => 2
a.count - 1 => 2

But

a.count -1 => 0

What causes this behavior? Why doesn’t it happen if a is an integer (and not an array)?

Also, I have noticed that there must not be a space between a method name and the parenthesis that follows (for parameters). Why is that?

Ruby 1.9.2

Answer 1

Because methods can be called with no parentheses, this:

a.count - 1

Means subtract 1 from a.count, whereas

a.count -1 # is like a.count(-1)

Means call the method a.count with -1 as an argument. It doesn’t happen when a is an integer because integers don’t have the count method. You just have to be careful as you type.