use strict;
use warnings;
use Data::Dumper;

sub are_hashes_equal {
   my ($hash1,$hash2)=@_;
   return 1 if $hash1==$hash2;
   my %temp=%$hash2;
   foreach my $key (keys %$hash1) {
     return 0 unless exists $temp{$key}
                and defined($hash1->{$key}) eq defined($temp{$key})
                and (defined $temp{$key} ? $temp{$key} eq $hash1->{$key} 
                                         : 1);
     delete $temp{$key};
   }
   return !keys(%temp);
}


my %aa=(uno=>1, due=>2,trio=>undef,quat=>0,cinq=>'');
my @b=(
       \%aa,
       {uno=>1, due=>2,trio=>undef,quat=>0,cinq=>''},
       {uno=>1, due=>2,trio=>0,quat=>undef,cinq=>''},
       {uno=>2, due=>2,trio=>undef,quat=>0,cinq=>''},
       {uno=>2, due=>2,trio=>undef,quat=>0},
       {uno=>2, due=>2,trio=>undef,quat=>0,cinq=>'',sex=>'is fun'},
      );

print Data::Dumper->Dump([\%aa],['*aa']);


foreach my $test_id (0..$#b) {

    print Data::Dumper->Dump([$b[$test_id]],['*test'.$test_id]);
    print "Is ",(are_hashes_equal(\%aa,$b[$test_id]) ? '' : 'not '),
          "the same as %aa\n\n";

}

##</code><code>##

%aa = (
        'cinq' => '',
        'trio' => undef,
        'due' => 2,
        'uno' => 1,
        'quat' => 0
      );
%test0 = (
           'cinq' => '',
           'trio' => undef,
           'due' => 2,
           'uno' => 1,
           'quat' => 0
         );
Is the same as %aa

%test1 = (
           'cinq' => '',
           'trio' => undef,
           'due' => 2,
           'uno' => 1,
           'quat' => 0
         );
Is the same as %aa

%test2 = (
           'cinq' => '',
           'trio' => 0,
           'due' => 2,
           'uno' => 1,
           'quat' => undef
         );
Is not the same as %aa

%test3 = (
           'cinq' => '',
           'trio' => undef,
           'due' => 2,
           'uno' => 2,
           'quat' => 0
         );
Is not the same as %aa

%test4 = (
           'trio' => undef,
           'due' => 2,
           'uno' => 2,
           'quat' => 0
         );
Is not the same as %aa

%test5 = (
           'cinq' => '',
           'trio' => undef,
           'due' => 2,
           'uno' => 2,
           'sex' => 'is fun',
           'quat' => 0
         );
Is not the same as %aa