Actually, perl will return an empty list, which if then evaluated in scalar context will return 0, which is boolean false. So if (my ($x, $y) = '12' =~ /(\d)

Actually, perl will return an empty list, which if then evaluated in scalar context will return 0, which is boolean false. So if (my ($x, $y) = '12' =~ /(\d)(\d)/) { <use $x and $y here> } is the normal idiom.