my $formget = qr(10-[KQ][A-Z0-9]*(?!/))i; while (my $form_type = ) { if ($form_type =~ /^$formget/ ) { print "Valid: $form_type"; } else { print "Invalid: $form_type"; } } __DATA__ 10-K 10-KSB 10-K405 10-ksb405 10-Q 10-K/A 10-Q/A #### Valid: 10-K Valid: 10-KSB Valid: 10-K405 Valid: 10-ksb405 Valid: 10-Q Invalid: 10-K/A Invalid: 10-Q/A