If TRUE, the function does not return until the operation has been completed. If FALSE and the operation is still pending, the function returns FALSE and the WSAGetLastError function returns WSA_IO_INCOMPLETE.
A pending operation is indicated when the function that started the operation returns FALSE and the WSAGetLastError function returns WSA_IO_PENDING
这里我想请教各位的是，对未完成的异步I/O请求进行这个API调用时，并且对对参数 fWait 传入 FALSE，获取的错误码究竟是 WSA_IO_INCOMPLETE ，还是 WSA_IO_PENDING ？
很感激对 3221225760 的解释
MSDN上的Windows Sockets Error Codes上有这样的描述：
WSA_IO_INCOMPLETE：Overlapped I/O event object not in signaled state.
The application has tried to determine the status of an overlapped operation which is not yet completed. Applications that use WSAGetOverlappedResult (with the fWait flag set to FALSE) in a polling mode to determine when an overlapped operation has completed, get this error code until the operation is complete.
WSA_IO_PENDING：Overlapped operations will complete later.
The application has initiated an overlapped operation that cannot be completed immediately. A completion indication will be given later when the operation has been completed.