怎样使用函数WSAAsyncSelect(SOCKET s,HWND hWnd,unsigned int wMsg,long lEvent)

int   OnAsyncEvent(HWND hwndDlg,WPARAM wParam,LPARAM lParam)
{
if(WSAGETSELECTERROR(lParam)==WSAENETDOWN)
{
MessageBox(hwndDlg,"The network subsystem has failed.","Error",MB_OK);
return 0;
} g_pbuff=new char[1024]; switch(WSAGETSELECTEVENT(lParam))
{
case FD_ACCEPT:
{
accept(accept_sd1,&sa_client,&sa_client_len);
WSAAsyncSelect(accept_sd1,hwndDlg,WM_ASYNCEVENT,FD_READ|FD_CLOSE|FD_WRITE);
}
break;
case FD_READ:
OnClientRead(hwndDlg,wParam,lParam);
break;
case FD_CLOSE:
OnClientClose(hwndDlg,wParam,lParam);
break;
}
return 0;
}