// Get the epoch timestamp for 6 months ago
$range_start = strtotime('6 months ago');
// Get the epoch timestamp for right now
$range_end = time();
$submitted_date = strtotime($_POST['yr'] . '-' .
$_POST['mo'] . '-' .
$_POST['dy']);
if (($range_start > $submitted_date) || ($range_end < $submitted_date)) {
$errors[] = 'Please choose a date less than six months old.';
}
?>