sub blah
{
  @array = match_files(\@array, \%hash);
  print "@array \n";
}

sub match_files
{
  @files = ();
  my($array, $hash) = @_;
  my(@array) = @$array;
  my(%hash) = %$hash;

  foreach $ary_element (@array)
  {
     foreach $hash_key( keys ( %hash ))
     {
         # do my comparison here
     }
     
     # if i get a match
     print "$ary_element\n"; # prints defined value
     push (@files, $ary_element);
     return @files;
   }
}
[download]

Your problem is that you try to return multiple times (every loop through the first foreach). This means that you end up returning an array with only one element. Put the return statement just before the end of the sub (after the foreach).

Added clarification.

Mad Hatter et al.,

Thank you very much for your help. Of course it had to be something utterly trivial like having return inside of a loop. doh!

The Mad Hatter has already pointed out the problem. Also it is better to return array ref instead of array. By doing that, you will gain much better performance. If you return array, Perl needs to duplicate the entire array, and that takes time.