通过 WSAIoctl(SOCKET s,DWORD dwIoControlCode,LPVOID lpvInBuffer,DWORD cbInBuffer,
  LPVOID lpvOutBuffer,DWORD cbOutBuffer,LPDWORD lpcbBytesReturned,
  LPWSAOVERLAPPED lpOverlapped,LPWSAOVERLAPPED_COMPLETION_ROUTINE lpCompletionRoutine);设置套接字的模式
WSAIoctl(sock,SIO_RCVALL,&dwbufferinlen,sizeof(dwbufferinlen),&dwbufferlen,sizeof(dwbufferlen),&dwbytesreturned,NULL,NULL); 
我已经在StdAfx.h中包含了#include <WINSOCK2.H>,为什么还会有下面的报错?
error C2065: 'SIO_RCVALL' : undeclared identifier指点一下,帮帮忙!