Array.-

Signature

array - other_array   #=> new_array

array - other_array returns new_array that contains the
difference of the
two arrays. In other words, new_array contains the elements that are in
array but not in other_array

Examples

a = [1,2,3,4,5,6,7,8,8,9,10]        #=> [1, 2, 3, 4, 5, 6, 7, 8, 8, 9, 10]
a - [1, 8]                          #=> [2, 3, 4, 5, 6, 7, 9, 10]
a - [-1, 22, 4, 9]                  #=> [1, 2, 3, 5, 6, 7, 8, 8, 10]

Documentation Reference

Ruby version 1.8.6

www.ruby-doc.org : Array.-