public static function getLength($str)
    {
        $bytes = 0;
        $chars = 0;
        while ($bytes < strlen($str)) {
            $charBytes = 1;
            if ((ord($str[$bytes]) & 0xC0) == 0xC0) {
                $charBytes++;
                if (ord($str[$bytes]) & 0x20 ) {
                    $charBytes++;
                    if (ord($str[$bytes]) & 0x10 ) {
                        $charBytes++;
                    }
                }
            }

            if ($bytes + $charBytes > strlen($str)) {
                // wrong character
                break;
            }

            $chars++;
            $bytes += $charBytes;
        }

        return $chars;
    }