#!/usr/bin/perl -w

use strict;

my @a = qw(a b c e);
my @b = qw(a b c d g);

compare1 (\@a,\@b);
compare2 (\@a,\@b);

sub compare1 
{
   my ($aref, $bref) = @_;
   
   my %a = map{$_=>0}@$aref;
   my %b = map{$_=>0}@$bref;
   
  foreach (keys %a)
   {
     $a{$_}++ if (exists ($b{$_})); 
   }
   
   foreach (keys %b)
   {
      $b{$_}++ if (exists $a{$_});   
   }
   
   foreach (keys %a)
   {
      print "$_ does not exist in B\n" if !$a{$_};
   }
   
   foreach (keys %b)
   {
      print "$_ does not exist in A\n" if !$b{$_};   
   }
}

sub compare2
{
   my ($aref, $bref) = @_;
   my @a = @$aref;
   my @b = @$bref;
   
   while (@a || @b)
   {
      my ($compa, $compb) = (shift @a, shift @b);
      $compa = 'undefined' if (!defined($compa)); 
      $compb = 'undefined' if (!defined($compb));
      if ($compa ne $compb)
      {  
         print "$compa and $compb do not match\n";
      } 
   }
}

__END__
e does not exist in B
g does not exist in A
d does not exist in A

e and d do not match
undefined and g do not match