#!/usr/bin/perl -w
use strict;
use warnings;
my %user = (
        1 => 'hallo|hallo|hallo|hallo|hallo',
        2 => 'hallo|hallo|hallo',
);
my %foo = (
        1 => 'hallo',
);
foreach my $user (
        grep {
                (split /\|/,$user{$_})[4] # das matcht auf garnichts
                #defined (split /\|/,$user{$_})[4] schmeisst Syntax und Implicit-Error
                        &&
                defined $foo{(split /\|/,$user{$_})[4]}
        }
        keys %user
) {
        print "Treffer: $user\n";
}