#!/usr/local/bin/perl5.9.5
#
use feature ":5.10";
use strict;
use warnings;


print "content-type: text/html\n\n";

my @userArray = qw(batman robin joker);
my @userArray2; #this is a null array

my @mainArray = (@userArray, @userArray2);

my @set;

# A loop, just for this example...
for(@mainArray)
{
    when ( ! defined $_ ) { next }
    when ( /^$/ ) { next }
    default { push @set, $_ }
}

say "@set";