Question

我在this thread上阅读指针别名规则，一个答案给出了以下示例，其中提到了endianness的潜在问题，我想知道是否有人可以给我什么字节序问题在以下代码中？

struct Msg
{
   unsigned int a;
   unsigned int b;
};

int main()
{
   // Pass data to something; if the implementer of this API were
   // strict-aliasing-aware, he would have taken a char*, not a unsigned int*
   Msg* msg = new Msg();
   msg->a = 1;
   msg->b = 2;

   // stupidBuffer is an alias for msg.
   // yes I know there are endianess problems here (WHY??), but my API is stupid and 
   // only works for one platform
   unsigned int* stupidBuffer = reinterpret_cast<unsigned int*>(msg);

   SendToStupidApi( stupidBuffer );   
}

Answer 1

没有任何字节序问题。只要StupidApi不涉及通过网络发送或平台之间的序列化，那么根本就没有字节序问题。

Answer 2

您的消息api应该允许您将本地endianess转换为网络endianess（通常是big endian）并返回。通过制定网络联结的惯例，任何机器都可以与网络上的任何一台机器通信，而不管它自己的字节顺序如何。

请查看您的api或示例。我不知道你在用什么，我担心我们无法帮助你。

为什么这里会出现字节序问题？

2 个答案: