UdpClient.SendTo Method

Sends datagram packets to a specified remote host and port.


public virtual int SendTo(byte[] datagram, int bytes, SocketFlags socketFlags, EndPoint remoteEP);
public virtual int SendTo(byte[] datagram, int bytes, SocketFlags socketFlags, IPEndPoint remoteEP);
public virtual int SendTo(byte[] datagram, int size, EndPoint remoteEP);
public virtual int SendTo(byte[] datagram, IPEndPoint remoteEP);
public virtual int SendTo(byte[] dgram, int bytes, IPEndPoint remoteEP);

Parameters

datagram: A byte array containing the data to be sent.
bytes: The number of bytes to send from the datagram buffer.
socketFlags: A combination of SocketFlags values that specify options for the send operation. See SocketFlags for details.
remoteEP: An EndPoint that represents the remote host and port to which you want to send the datagram. This parameter can be an IPEndPoint.
size: The number of bytes to send from the datagram buffer.
dgram: A byte array containing the data to be sent.

Return Value

The number of bytes sent to the Socket.

Exceptions

ArgumentNullException: datagram is null.
ArgumentOutOfRangeException: bytes is less than 0 or greater than the size of the datagram buffer.
ObjectDisposedException: The UdpClient has been closed.
SocketException: An error occurred while accessing the socket. See SocketException for details.
NotSupportedException: The SocketFlags value is not supported.

Note: The SendTo method is used to send UDP datagrams to a specific remote host and port. If you do not specify a remote endpoint when you create the UdpClient, you must specify one when you call the SendTo method.

Example


using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class UdpSendExample
{
    public static void Main(string[] args)
    {
        try
        {
            // Creates a UdpClient for sending and receiving datagrams.
            using (UdpClient udpClient = new UdpClient())
            {
                // You can optionally bind to a local port if you need to receive responses.
                // udpClient.Client.Bind(new IPEndPoint(IPAddress.Any, 11000));

                // Data to send.
                byte[] datagram = Encoding.ASCII.GetBytes("Hello, UDP!");

                // Remote endpoint: IP address and port of the destination.
                IPEndPoint remoteEP = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 11001);

                Console.WriteLine($"Sending UDP datagram to {remoteEP.Address}:{remoteEP.Port}");

                // Sends a datagram to the specified endpoint.
                int bytesSent = udpClient.SendTo(datagram, datagram.Length, remoteEP);

                Console.WriteLine($"Successfully sent {bytesSent} bytes.");
            }
        }
        catch (Exception e)
        {
            Console.WriteLine($"An error occurred: {e.Message}");
        }
    }
}