TAJ szám validálás (Validation function for hungarian Social Security Number (TAJ))

TAJ_szam_validalas.php

<?php

/**
 * Validation function for hungarian Social Security Number (TAJ).
 *
 * @param string $ssn
 *   The hungarian Social Security Number (TAJ).
 *
 * @return bool
 *   TRUE, if the number is valid. Otherwise FALSE.
 */
function validate($ssn) {
  $ssn = preg_replace("/[^0-9]/", "", $ssn);
  $length = strlen($ssn);

  if ($length !== 9) {
    return FALSE;
  }

  $sum = 0;
  $num = '';

  for ($i = 0; $i < $length; $i++) {
    if ($i < 8) {
      $sum += (($i % 2 == 0) ? $ssn[$i] * 7 : $ssn[$i] * 3);
      $num .= $ssn[$i];
    }
  }

  $num .= $sum % 10; // CDV
  return $ssn === $num;
}

It works for me only if I replace == to != in line 25.

The CDV computation method is not correct in the line 30. The right one would be the following: $num .= ($i % 10 == 0) ? 0 : 10 - ($sum % 10);