udp发送数据和接收的对不上，下面是一段发送和接收，接受的0xFF变成了0

switch (m_Send)
{
case CONNECTION:
senddata[0] = 8;//---长度
senddata[1] = 0xff;//---目标
senddata[2] = PC_NUM;//---源
senddata[3] = CONNECTION;//---类型码
senddata[4] = GetCheckSum(senddata, 4);//---校验和
err = sendto(
UDPSocket,
reinterpret_cast<char *>(senddata),
10,
0,
(const sockaddr *)&s_RemoteAddr,
sizeof(s_RemoteAddr)
);
//err = WSAGetLastError();
//err = send(UDPSocket, reinterpret_cast<char *>(senddata), 10, 0);
if (err == SOCKET_ERROR)
{
MessageBox(_T("发送失败"));
return FALSE;
}

//udp1DataReceived();
break;//---发送






err = recvfrom(
UDPSocket, /* receive UDP data */
reinterpret_cast<char *>(RecvBuf),
BufLen,
0,
(sockaddr *)&s_RemoteAddr,
(int *)&sockaddrlen
);
if (err == SOCKET_ERROR) /* Is receive data right */
{
MessageBox(_T("receive data is failure!"));
UpdateData(FALSE);
return 0;
}

break;