他是如何绕过注册10字符限制的？

public function transform($txt)
    {
        $txt = trim($txt);
        $txt = addslashes(htmlspecialchars($txt, ENT_QUOTES, "UTF-8"));
        if (preg_match_all("/Quote:(.+?)[/quote]/is", $txt, $match)) {
            $txt = preg_replace('/s*rns*/', '', $txt, 1);
        }
        $huanhang = array(
            "rn",
            "n",
            "r"
        );
        $txt      = str_replace($huanhang, '<br>', $txt);