sub spandiffstr { my ( $old, $new ) = @_; my $span = ''; my $espan = ''; ( $old ^ $new ) =~ /^\0*/ and my $subscr = $+[0]; substr $old, $subscr, 0, $span; substr $new, $subscr, 0, $span; my ( $rold, $rnew ) = map scalar reverse, $old, $new; ( $rold ^ $rnew ) =~ /^\0*/ and my $lsubscr = -$+[0]; my $losubscr = $lsubscr; unless ($lsubscr) { $losubscr = length $old; $lsubscr = length $new; } substr $old, $losubscr, 0, $espan; substr $new, $lsubscr, 0, $espan; return $old, $new; }