if ((($month, $day, $year) = /($month)($day)($year)/io) ||
    (($day, $month, $year) = /($day)($month)($year)/io)) {
....
}

##</code><code>##


             JANUARY  => 'Jan',
             FEB      => 'Feb',
             FEBRUARY => 'Feb',
             ....
             DEC      => 'Dec',
             DECEMBER => 'Dec');

##</code><code>##

printf('%02d-%s-%04d', $day, $mhash{uc $month}, $my_year);

##</code><code>##

my %mhash = (JAN      => {Name => 'Jan', Days => 31},
             ....

##</code><code>##

printf('%02d-%s-%04d', $day, $mhash{uc $month}{Name}, $my_year);