Are you looking for different keys, keys/value pairs or both?

One option is iterate through both hashes in-sync (much like the "merge" step in a mergesort) and spit out any differences. What I present below is meant as more of an algorithm than an actual implementation (though it does work). It could be tweaked quite a bit in actual implementation to get much better performance. This is probably not the best perl implementation, but it is a good general-purpose algorithm for doing "diffrence of lists/difference of hashes". 

   my @k1=sort keys %h1;
   my @k2=sort keys %h2;
   my $k1;
   my $k2;
   while((scalar @k1 > 0)&&(scalar @k2 > 0)){
     if(!defined $k1){
       $k1=shift @k1;
     }
     if(!defined $k2){
       $k2=shift @k2;
     }
     if($k1 eq $k2){
       if($h1{$k1} ne $h2{$k2}){
#          .. keys match but contents dont
       }
       undef $k1;
       undef $k2;
     }elsif($k1 lt $k2){
#       .. key in k1 and not in k2
       undef $k1;
     }else{
#       .. key in k2 and not in k1
       undef $k2;
     }
   }
   if(defined $k1){
     foreach ($k1,@k1){
#       .. key in k1 and not in k2
     }
   }
   if(defined $k2){
     foreach ($k2,@k2){
#       .. key in k2 and not in k1
     }
   }

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In reply to RE: diff of two hashes. by lhoward
in thread diff of two hashes. by ChuckularOne

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