#!/usr/bin/perl
print "content-type: text/html \n\n";

use strict;
use warnings;

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

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

my @set = map { exists($_)? $_ : delete($_) } @mainArray;

#@set should consist "batman robin joker", but not
#"batman robin joker NULL"

print qq[@set\n];