use strict;
my @ar1 = ('eins', 'zwei', 'drei', 'vier');
my @ar2 = ('null', 'vier', 'sieben', 'eins');

my @schnitt = array_schnitt(\@ar1, \@ar2);

print "@schnitt";

sub array_schnitt {
    my $ar1 = shift;
    my $ar2 = shift;

    my @result = ();

    for my $elem (@$ar1) {
        push @result, $elem if grep $elem eq $_, @$ar2;
    }

    return @result;
}