C / C++ / MFC

void post_io_request_of_accept(SOCKET so_listen, PerIoData * per_io_data)
{
	DWORD bytes_received;	
	BOOL ok = AcceptEx(so_listen,
		per_io_data->so_local,
		per_io_data->buf,
		0,
		sizeof(SOCKADDR_STORAGE)+16,
		sizeof(SOCKADDR_STORAGE)+16,
		&bytes_received,
		per_io_data);
	DWORD err = GetLastError();
	if (ok)
	{
		assert(false);
	}
	else if (err==ERROR_IO_PENDING)
	{
	}
	else
		assert(false);
}

DWORD WINAPI ServingThreadProc(LPVOID pParam)
{
	DWORD bytes_tranfered;
	ULONG_PTR completion_key;
	PerIoData * per_io_data;

	while (true)
	{
		BOOL ok = GetQueuedCompletionStatus(HANDLE(pParam),
			&bytes_tranfered,
			&completion_key,
			(OVERLAPPED**)&per_io_data,
			INFINITE);
		assert(ok);		
		handle_io_completion(per_io_data);
	}
	return 0;
}

int main()
{
	WSADATA wsa;
	int res = WSAStartup(MAKEWORD(2,2), &wsa);
	assert(res==0);

	SOCKADDR_IN addr_in;
	addr_in.sin_family = AF_INET;
	addr_in.sin_addr.s_addr = inet_addr("127.0.0.1");
	addr_in.sin_port = htons(5150);
	ZeroMemory(&addr_in.sin_zero, sizeof(addr_in.sin_zero));

	SOCKET s = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, 0);
	assert(s!=INVALID_SOCKET);
	int ok = connect(s, (sockaddr*)&addr_in, sizeof(addr_in));
	assert(ok==0);

	for (int i=0; i<10; ++i)
	{
		char buf[256];
		sprintf_s(buf, sizeof(buf), "message %d", i);
		WSABUF wsa_buf;
		wsa_buf.buf = buf;
		wsa_buf.len = strlen(buf);
		DWORD bytes_sent;
		int res = WSASend(s, &wsa_buf, 1, &bytes_sent, 0, NULL, NULL);
		assert(res==0 && bytes_sent==wsa_buf.len);
		printf_s("sent: %s\n", buf);
		Sleep(1000);
	}

	WSACleanup();

	return 0;
}