WinSocket的问题:非阻塞模式recv返回-1,WSAGetLastError 返回 0

[重新注册]

尝试非阻塞的socket编程，碰到WSAGetLastError()一直是返回值为0的问题，百度了几个博客，都说是因为WSAGetLastError()的调用必须及时，不能被其他的系统调用隔开，否则得到的错误值被掩盖。
如博客： http://blog.csdn.net/tianbaowen/article/details/8485567
然而，我的代码在recv()后紧跟着的系统调用就是WSAGetLastError(),却依然得到的是返回值0。最后上了国外的网站看，有人说是需要直接调用GetLastError()就可以，结果一改，果然就得到了10035，现在还不知道为何。。。

DWORD IniSOCKDLL()
{
	WORD wVersionRequested;
	WSADATA wsaData;
	int err=0;

	wVersionRequested = MAKEWORD( 2, 2 );
	err = WSAStartup( wVersionRequested, &wsaData ); 
	if(err != 0)
		return err;
	if ( LOBYTE( wsaData.wVersion ) != 2 ||
		HIBYTE( wsaData.wVersion ) != 2 ) {
		WSACleanup( );
		err = -1;
	}
	return err;
}

int main()
{
	int status;
	IniSOCKDLL();
	SOCKET sc=socket(AF_INET,SOCK_STREAM,0);
	
	SOCKADDR_IN addr;
	int len;
	addr.sin_family=AF_INET;
	addr.sin_addr.s_addr = inet_addr("127.0.0.1");
	addr.sin_port = htons(21050);
	len = sizeof(addr);
	cout << "start client" << endl;
	status = ::connect(sc, (struct sockaddr *)&addr, len);//server已开启，连接server端

	char buff[1024];
	ZeroMemory(buff,1024); 
	memcpy(buff,"linking",7);


	u_long iMode = 1;//非阻塞模式
	ioctlsocket(sc, FIONBIO, &iMode);//设置套接字sc为非阻塞模式
	len = send(sc,buff, strlen(buff),0);
	while(!quit){
		len = recv(sc, buff, 1024, 0);
		if(len < 0){
			int err = GetLastError();//改成这个就好使； 用WSAGetLastError()就一直是0
			if(err == WSAENETDOWN || err == WSAECONNRESET || err == WSAENOTCONN){//断线重连
				closesocket(sc);
				sc = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, NULL);
				int status = ::connect(sc, (struct sockaddr *)&addr, sizeof(addr));
				if(status < 0){
					Sleep(3000);
				}else{
					memcpy(buff,"linking",7);
					ioctlsocket(sc, FIONBIO, &iMode);
					send(sc,buff,7,0);
				}
			}else if(err == WSAEWOULDBLOCK){
				Sleep(10);
			}
			continue;
		}
		send(sc, "received", strlen("received"), 0);
		if(strncmp(buff,"left",4) ==0){
			cout << "left" << endl;
		}else if(strncmp(buff,"right",5)==0){
			cout << "right" << endl;
		}
		ZeroMemory(buff, 1024);

	}//while

	closesocket(sc);
	cout << "stopped..." << endl;
        return 0;
}

[赵4老师]

10035 无法立即完成一个非阻止性套接字操作。

[赵4老师]

Windows的bug，试试安装最新的SP。我猜。