lua调用c++类里的函数 报错

Cocos2d-x
#1

我定义的c++类 名称就是
class Myxxtea
{
…
…
unsigned char *xxtea_encrypt(unsigned char *data,uint32_t data_len, unsigned char *key,uint32_t key_len,uint32_t *ret_length);
}

用tolua++把自定义c++导出给lua调用
lua脚本里调用：
local datak=“2dxLua”
local datak_len=string.len(datak)
local keyk=“XXTEA”
local keyk_len=string.len(keyk)
local retk_length=0
Myxxtea:xxtea_encrypt(datak,datak_len,keyk,keyk_len,retk_length)
报错 ：传的参数无效

#2

http://blog.csdn.net/song_hui_xiang/article/details/15712417