months_between_dates.rb

#!/usr/bin/env ruby
require 'date'

def months_between(start, stop)
  diff = (stop - start)
  (diff/30).floor.to_i + (diff % 30 > 15 ? 1 : 0)
end

(0..12).each do |i|
  (0..100).each do |j|
    start = Date.new(2011,12,1) >> i
    stop = (start >> 2) + 1
    start = start + j
    puts "There are #{months_between(start,stop)} months between dates #{stop - start} days apart."
  end
end