微信支付的随机字符串

noncestr

    //作用：产生随机字符串，不长于32位
    private function createNoncestr($length = 32) {
        $chars = "abcdefghijklmnopqrstuvwxyz0123456789";
        $str = "";
        for ($i = 0; $i < $length; $i++) {
            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
        }
        return $str;
    }