/** * Get the Checkdigit Part of ISBN Number * * @return string|false Checkdigit or false if failed */ function getCheckdigit() { $ver = $this->getVersion(); $check = false; switch ($ver) { case ISBN_VERSION_ISBN_10: $check = ISBN::_checkdigitISBN10($this->_getISBNBody()); break; case ISBN_VERSION_ISBN_13: $check = ISBN::_checkdigitISBN13($this->_getISBNBody()); break; } return $check; }