sub deDuppedArray
{
    my ($a_ref, $b_ref, $my_bonly, $my_isec_plus_bonly) = @_; # refere
+nce
    my (%Aseen, %Bseen, %count, @isec, @diff, @union, @aonly) = ();
    @Aseen{@$a_ref} = (); # lookup table
    @Bseen{@$b_ref} = (); # lookup table
    foreach my $e (@$a_ref, @$b_ref) { $count{$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(@aonly, $e) unless exists $Bseen{$e}; # seen once + f
+rom A = Aonly
            push(@$my_bonly, $e) unless exists $Aseen{$e}; # seen once
+ + from A = Aonly
        }
    }
    @$my_isec_plus_bonly = ( @isec, @$my_bonly);
}
[download]

my @x = ("z", "y", "z");
@x = ();
[download]

Doesn't the @x get initialize here? If I want to reuse @x what do I do to initialize, is there another way?

Yes @x gets initialized there, but ("z", "y", "z") is different than (), and my @x is different than my ( @x, @y, @z ).

What do you think my ( @x, @y, @z ) = ("z", "y", "z"); does?

I am sorry I have no idea what that does. Please explain. My guess is @x[0]=z, @y[0]=y and @z[0]=z.

When I had the below statement, I was trying to create and initialize values of all variables.

my (%Aseen, %Bseen, %count, @isec, @diff, @union, @aonly) = ();

Please let me know what I'm doing wrong.

Thanks for your help.