Prado\Security\TSecurityManager::strlen PHP Метод

If available uses the multibyte string function mb_strlen.

private strlen ( string $string ) : integer
$string	string	the string being measured for length
Результат	integer	the length of the string

    private function strlen($string)
    {
        return $this->_mbstring ? mb_strlen($string, '8bit') : strlen($string);
    }

TSecurityManager