On Dec 9, 2005, at 12:48 PM, Sam Dela Cruz 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:
>
> ##### Perl code
> %hash = {};
> while (<>)
> {
>     chomp;
>         $hash{$_}++;
> }
>
> foreach my $key (sort keys %hash)
> {
>     print "$key: $hash{$key}\n" if ($hash{$key} > 1);
> }
>
> I tried to translate this in Ruby, but could not find en equivalent of
> $hash{$_}++, this is auto increment.

See if this gets you going:

   seen = Hash.new(0)
   ARGF.each_line { |line| seen[line.strip] += 1 }

   seen.each { |key, value| puts key if value > 1 }

James Edward Gray II