use strict;
use warnings;

my $count = 0;

for my $s(chr(13) . chr(10),
          chr(10) . chr(13),
          chr(10)          ,
          chr(13)          ,
          '0' . chr(13) . chr(10),
          '0' . chr(10) . chr(13),
          '0' . chr(10)          ,
          '0' . chr(13)          , ) {

    $count++;  
    print "$count match\n" if ($s && $s =~ m![[:cntrl:]]+!);
}

##</code><code>##

1 match
2 match
3 match
4 match
5 match
6 match
7 match
8 match