C / C++ / MFC

case WM_SOCKET:

            // Determine whether an error occurred on the
            // socket by using the WSAGETSELECTERROR() macro

            if (WSAGETSELECTERROR(lParam))
            {
                // Display the error and close the socket
                closesocket(wParam);
                break;
            }

            // Determine what event occurred on the
            // socket

            switch(WSAGETSELECTEVENT(lParam))
            {
                case FD_ACCEPT:

                    // Accept an incoming connection
                    Accept = accept(wParam, NULL, NULL);

                    // Prepare accepted socket for read,
                    // write, and close notification

                    WSAAsyncSelect(Accept, hWnd, WM_SOCKET,
                        FD_READ | FD_WRITE | FD_CLOSE);
                    break;

                case FD_READ:

                    MessageBox(NULL, "FD_READ", "FD_READ",MB_OK);
                    break;

                case FD_WRITE:
		MessageBox(NULL, "FD_WRITE", "FD_WRITE",MB_OK);
                    break;

                case FD_CLOSE:

                    MessageBox(NULL, "FD_CLOSE", "CLOSE",MB_OK);
                    closesocket(wParam);
                    break;
            }
            break;