缓冲存储器分配

Question

I've got problems with buffer memory allocation. I have WF chat application with two threads: one sending, one receiving. First client sends message to the server:

    private async void send_button_Click(object sender, EventArgs e)
    {
        string msg = this.messageTextBox.Text.Trim();
        await Task.Run(() =>
        {
            buf = Encoding.ASCII.GetBytes(msg); //buf-buffer for send/rcv
            clientSock.SendTo(buf, servEP);
            this.Invoke((Action)delegate
            {
                this.dialogTextBox.Text += string.Format("client: {0}", 
                      this.messageTextBox.Text.Trim());
            });
         buf = new byte[1024]; //allocate memory for receiving
        });
    }

Then server responds, and here I get a problem with buffer:

    private async void Form1_Load(object sender, EventArgs e)
    {
        clientSock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, 
                             ProtocolType.Udp);
        servIPEP = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 50000);
        servEP = (EndPoint)servIPEP;

        clientIPEP = new IPEndPoint(IPAddress.Any, 43000);
        clientEP = (EndPoint)clientIPEP;
        clientSock.Bind(clientEP);
        while (true)
        {
            await Task.Run(() =>
            {
                //buf = new byte[1024] I tried to allocate here, but it's not working.

                int rcv = clientSock.ReceiveFrom(buf, 0, buf.Length, 
                    SocketFlags.None, ref servEP); // it returns right int value!
                msg = Encoding.ASCII.GetString(buf, 0, rcv); //but buf is empty..
                this.Invoke((Action)delegate
                {
                    this.dialogTextBox.Text += rcv;
                    this.dialogTextBox.Text += string.Format("server: {0},rcv: {1}", 
                        msg, rcv) + Environment.NewLine; //msg is empty...
                });
            });
        }
    }

It is really strange, because if the server re-sends the message, it receives in the client without a problem. But first message always null. In fact it receives the first message, I tested

int rcv = clientSock.ReceiveFrom(buf, ref servEP);

it returns right int, but buf values are zeros.

Answer 1

What is buf.Length? Also the line buf = new byte[1024]; //allocate memory for receiving confuses me

Could you check what the size is the first time you run? Maybe its zero? I don't see where you declared it which is why its bothering me. Why don't you write var buf2 = new byte[1024]; and change all the buf to buf2. Actually cant you simply write byte[] buf instead of buf =? and why doesnt it work? It cant be a compile error?

-was a comment but i have a feeling this may solve so. I'll delete if it isn't the case-