From: John W Higgins <wishdev@...>
Date: 2009-10-27T04:15:59+09:00
Subject: Re: Hash Reverse ?

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Good Morning,

On Mon, Oct 26, 2009 at 5:59 AM, salai <sayakyi@gmail.com> wrote:

> I am preparing for my orals exam in Ruby (my last chance.. , If I fail
> the test, no more possible to study Computer Science related :-) )
>
> http://codepad.org/foNb9Pd3
>
> class Hash
>        def hash_revert
>                hash_new = Hash.new
>                self.each {|key,value|
>                        if not hash_new.has_key?(key) then hash_new[value] =
> key end
>                }
>                return hash_new
>        end
> end
>
> h = {2=>"a", 1=> "b", 3 =>"a", 4=> "a", 5 => "b", 6=>"c"}
> p h.hash_revert #--> {"a"=>4, "b"=>1, "c"=>6}
>
> or Should I get this ??
> # => {"a"=>2, "b"=>1, "c"=>6}
>
>
The answer can be different (and most likely will be) under 1.8 and 1.9 - in
1.8 order is not guaranteed - but in 1.9 it is (order of insertion into the
hash) and therefore under 1.9 you will get the second option and apparantly
under 1.8 you get your first.

John

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