如何使用PHP验证PAN No和银行帐号？

I need to validate pan number and bank account number fields. How can I do that using php? I have to implement this validation in civicrm custom form. civicrm has any built in function for these two validations.

Pan number validation regular expression

if (!preg_match("/^([a-zA-Z]){5}([0-9]){4}([a-zA-Z]){1}?$/", $pannumber)) {
  echo "Invalid pan number";
}