On 12/9/05, Sam Dela Cruz <sam.dela.cruz / philips.com> wrote:
> Hi,
>
> I'm starting to use Ruby in one of my projects at work.  I'm coming from a
> Perl background.
> In my project I would need to parse a list of numbers (thousands of them)
> and then return the duplicates.  In perl, I can do this:
>
[elided perl goo]
>
> I tried to translate this in Ruby, but could not find en equivalent of
> $hash{$_}++, this is auto increment.
> Can somebody tell me how this is to be done in Ruby?

translating from Perl to Ruby seems often to be a bad idea ... a
common idea, but not necessarily a good one.   I'd rather work
with a Ruby solution to a problem than a Rubification of a Perl
solution to a problem.

> Or maybe the Ruby
> way on how to attack this whole thing.  Thanks.

I'm assuming that your list comes from a file (but you can change that
pretty easily in the code below), given that, how about something like:


seen_ary = Array.new

File.open("nums","r").each do |elem|
  print elem if seen_ary.include?(elem)
  seen_ary.push(elem)
end

(there are probably still better ways of doing this though)

>
> Regards,
> Sam
>


--
thanks,
-pate
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