c:\@Work\Perl>perl -wMstrict -e "my @strings = qw(DOG COT BAL MAN); ;; use constant FMT => '%6s'; ;; printf FMT, $_ for '', @strings; print qq{\n}; ;; for my $row (@strings) { printf FMT, $row; for my $col (@strings) { my $d = diff($row, $col); printf FMT, $d; } print qq{\n}; } ;; sub diff { return scalar ($_[0] ^ $_[1]) =~ tr/\0//c; } " DOG COT BAL MAN DOG 0 2 3 3 COT 2 0 3 3 BAL 3 3 0 2 MAN 3 3 2 0