using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace WindowsApplication11
{
    public delegate void love(string txt);
    
    public partial class Form1 : Form
    {
        private AsyncCallback callback;    

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            callback = new AsyncCallback(m);
            
        }

        private void button1_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            string addr = textBox1.Text;
            object state = new object();
            Dns.BeginGetHostEntry(addr, callback, state);
        }
        private void m(IAsyncResult ar)
        {
            
            IPHostEntry ipHost = Dns.EndGetHostEntry(ar);
            foreach (IPAddress ip in ipHost.AddressList)
            {
                if (this.listBox1.InvokeRequired)
                {
                    love set = new love(write);
                    this.Invoke(set, new object[] { ip.ToString() });
                }
                else
                {
                    listBox1.Items.Add(ip.ToString());
                }
            }
        }
        
        private void write(string txt)
        {
            listBox1.Items.Add(txt);
        }
    }
}