From: Jean-Julien Fleck <jeanjulien.fleck@...>
Date: 2010-08-22T01:27:59+09:00
Subject: Re: A small problem for arrays

2010/8/21 Unc88 Unc88 <unc88@mail.ru>:
> Can do the subtraction of arrays without using the operator "-"?
> Is there a standard method in the class Array?

"-" *is* a standard method of class Array. The apparent "operator"
behavior is just syntaxic sugar added on it:

>> a1 = (1..10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>> a2 = (5..7).to_a
=> [5, 6, 7]
>> a1.-(a2)
=> [1, 2, 3, 4, 8, 9, 10]

Last line call "-" method of object "a1" with object "a2" as an argument.

~> ri Array.-

---------------------------------------------------------------- Array#-
     array - other_array    -> an_array
------------------------------------------------------------------------
     Array Difference---Returns a new array that is a copy of the
     original array, removing any items that also appear in other_array.
     (If you need set-like behavior, see the library class Set.)

        [ 1, 1, 2, 2, 3, 3, 4, 5 ] - [ 1, 2, 4 ]  #=>  [ 3, 3, 5 ]

Cheers,

-- 
JJ Fleck
PCSI1 Lycée Kléber