Question

When using the triple dot notation in a ruby Range object, I get this:

(0...5).each{|n| p n}
0
1
2
3
4

When I use the ‘last’ method I get:

(0...5).last
 => 5 

I would have expected 4

Is this is a bug? Or is there something I don’t understand about the the concept of a Range object?

Answer 1

This is by design. The Ruby 2.0 documentation is more specific:

Note that with no arguments last will return the object that defines the end of the range even if exclude_end? is true.

(10..20).last      #=> 20
(10...20).last     #=> 20
(10..20).last(3)   #=> [18, 19, 20]
(10...20).last(3)  #=> [17, 18, 19]