为什么加上WSAAsyncSelect后，socket就不能连接服务器了？

[f_liu]

#define WM_SOCKET WM_USER+100

	if(WSAAsyncSelect(s, this->m_hWnd, WM_SOCKET, FD_READ | FD_ACCEPT | FD_WRITE | FD_CLOSE) == SOCKET_ERROR)
	{
		MessageBox("注册异步失败!!");
	}

	if (::connect(s, (sockaddr*)&addr, sizeof(addr)) != SOCKET_ERROR)
	{
		GetDlgItem(IDC_SHOW)->GetWindowText(str);
		str += "连接服务器成功! \r\n";
		GetDlgItem(IDC_SHOW)->SetWindowText(str);

		GetDlgItem(IDC_Send)->EnableWindow(TRUE);
		GetDlgItem(IDC_SendMsg)->EnableWindow(TRUE);
		GetDlgItem(IDC_Port)->EnableWindow(FALSE);
		GetDlgItem(IDC_Connect)->EnableWindow(FALSE);
		GetDlgItem(IDC_EDIT1)->EnableWindow(FALSE);
	}
	else
	{
		GetDlgItem(IDC_SHOW)->GetWindowText(str);
		str += "连接服务器失败!\r\n";
		GetDlgItem(IDC_SHOW)->SetWindowText(str);

	}

如果把WSAAsyncSelect去掉是可以连接服务器的，加上就一直是连接服务器失败

[赵4老师]

参考MSDN98\SAMPLES\VC98\SDK\NETDS\WINSOCK\WSOCK\WSOCK.C http://bbs.csdn.net/topics/390374955

[ningto.com]

WSAAsyncSelect会将socket设置为非阻塞模式，然后看MSDN上说的connect非阻塞模式下的返回值

[ningto.com]

With a nonblocking socket, the connection attempt cannot be completed immediately. In this case, connect will return SOCKET_ERROR, and WSAGetLastError will return WSAEWOULDBLOCK. In this case, there are three possible scenarios: Use the select function to determine the completion of the connection request by checking to see if the socket is writeable. If the application is using WSAAsyncSelect to indicate interest in connection events, then the application will receive an FD_CONNECT notification indicating that the connect operation is complete (successfully or not). If the application is using WSAEventSelect to indicate interest in connection events, then the associated event object will be signaled indicating that the connect operation is complete (successfully or not).

[ningto.com]

在WM_SOCKET消息函数里面判断收到FD_CONNECT通知表示连接成功，不能根据connect返回值来判断

[f_liu]

引用 4 楼 tujiaw 的回复:

在WM_SOCKET消息函数里面判断收到FD_CONNECT通知表示连接成功，不能根据connect返回值来判断

那个问题解决了……问题是现在在服务器中接受不到accept等的消息