关于C#的UDP编程。

Question

UdpClient receivingUdpClient = new UdpClient();
没有指定端口 
----------------------IPEndPoint RemoteIpEndPoint ;
RemoteIpEndPoint=null ；Byte[] receiveBytes = receivingUdpClient.Receive(ref RemoteIpEndPoint); 

Answer 1

你忘记了最重要的一句：
UdpClient.JoinMulticastGroup(GroupAddress);
private static readonly IPAddress GroupAddress = IPAddress.Parse("224.168.100.2");
private const int GroupPort = 11000;
listener.JoinMulticastGroup(GroupAddress);
listener.Connect(groupEP);
...
while (!done)
{
    Console.WriteLine("Waiting for broadcast");
    byte[] bytes = listener.Receive( ref groupEP);    Console.WriteLine("Received broadcast from {0} :\n {1}\n",
            groupEP.ToString(),
            Encoding.ASCII.GetString(bytes,0,bytes.Length));
}