$a + $b = $b + $a #### kabel@linux:~> perl my ($z1, $z2) = qw/ z9 Z9 /; print ++ $z1, ", ", ++ $z2, $/; aa0, AA0 kabel@linux:~> #### ++: /\A[A-Z]*[0-9]*\z/ -> /\A[A-Z]*[0-9]*\z/ ++: /\A[a-z]*[0-9]*\z/ -> /\A[a-z]*[0-9]*\z/