&buf 是一个 const uint8_t **.您真正想要做的是将 buf 传递给 serverAnswer，您需要一个 const_cast 以允许从 const进行转换code> 指向 void* 的指针:

&buf is a const uint8_t **. What you actually want to do is pass buf to serverAnswer, you'll need a const_cast to allow conversion from a const pointer to void*:

const uint8_t* buf;
serverAnswer(const_cast<uint8_t*>(buf), buf_len);

为了避免未定义的行为，您应该将 const 放回 serverAnswer:

To avoid undefined behaviour you should put the const back in serverAnswer:

void serverAnswer(void *pUserData, int flag) {

const uint8_t* p = (const uint8_t *)pUserData;
uint8_t data = p[0];

}