# Calling
deDuppedArray(\@currentListing, \@previousListing, \@bonly, \@isec_plus_bonly);

##</code><code>##

sub deDuppedArray
{
    my $a_ref = shift; # reference to input array A
    my @a = @$a_ref; # input array A
    my $b_ref = shift; # reference to input array B
    my @b = @$b_ref; # input array B
    my $bonly_ref = shift; # input array Bonly
    my @my_bonly = @$bonly_ref; # input array Bonly
    my $isec_plus_bonly_ref = shift; # input array isec_plus_bonly
    my @my_isec_plus_bonly = @$isec_plus_bonly_ref; # input array isec_plus_bonly

    my (%Aseen, %Bseen) = ();
    @Aseen{@a} = (); # lookup table
    @Bseen{@b} = (); # lookup table

    my (%count, @isec, @diff, @union, @aonly) = ();
    @my_bonly = (); # create null arrays

    foreach my $e (@a, @b) { $count{$e}++ } # put all items in hash table

    foreach my $e (keys %count)
    { # interate over each key of hash table
        push(@union, $e); # keys of hash table = union
        if ($count{$e} == 2)
        {
            push @isec, $e; # seen more than once = intersection
        } else
        {
            push @diff, $e; # seen once = difference
            push(@aonly, $e) unless exists $Bseen{$e}; # seen once + from A = Aonly
            push(@my_bonly, $e) unless exists $Aseen{$e}; # seen once + from A = Aonly
        }
   }
    @my_isec_plus_bonly = ( @isec, @my_bonly);
}