my @stack = ".";
while(my $cd = pop @stack) {
    opendir(my $dh, $cd) or die("bad dir - $!");
    foreach (readdir($dh)) {
        next if /^\./;
        print $_.$/;
        push @stack, "$cd/$_" if -d "$cd/$_";
    }
}

##</code><code>##

&traverse(".");
sub traverse {
    my $dir = shift;
    opendir(my $dh, $dir) or die("bad dir - $!");
    foreach (readdir($dh)) {
        next if /^\./;
        print $_.$/;
        &traverse("$dir/$_") if -d "$dir/$_";
    }
}