#!/usr/bin/perl -w
use strict;
use warnings;

my %hash = (foo => defined, bar => defined, foobar => defined,);
print "Altes \"Array\": " . (join ' ',keys (%hash)) . "\n";
local $/ = "\n";
while (<DATA>) {
	chomp;
	print "Untersuche $_...";
	if (exists $hash{$_}) { print "haben wir schon\n" }
	else { print "nehmen wir\n"; $hash{$_} = defined }
}
print "Neues \"Array\": " . (join ' ',keys (%hash)) . "\n";

__DATA__
0foo
foo
bar
foofoo
barbar
foobar