Nice solution; ++tye.

Changing

        $len= length( ( $dif =~ /^(\0+)/ )[0] );
[download]

to

        $len= length( ( $dif =~ /^(\0+)/ )[0] || '' );
[download]

will make it run quiet under warnings when the common prefix is the empty string.

-sauoq
"My two cents aren't worth a dime.";