form1.cs

这是.net2005学习不可缺少的教程

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;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            DnsPermission p = new DnsPermission(System.Security.Permissions.PermissionState.Unrestricted);
            p.IsUnrestricted();

            try
            {
                this.textBox1.Text = Dns.GetHostName();

                IPHostEntry myIPHost = new IPHostEntry();

                myIPHost = Dns.GetHostEntry(this.textBox1.Text);
                for(int i = 0; i<myIPHost.AddressList.Length; i++)
                {
                    this.textBox2.Text = myIPHost.AddressList[i].ToString();
                }
            }
            catch { }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if (this.textBox1.Text == string.Empty && this.textBox2.Text != string.Empty)
            {
                IPAddress myIP = IPAddress.Parse(this.textBox2.Text);

                IPHostEntry myHost = new IPHostEntry();
                myHost = Dns.GetHostEntry(myIP);
                this.textBox1.Text = myHost.HostName;
            }
            else if (this.textBox1.Text != string.Empty && this.textBox2.Text == string.Empty)
            {
                IPHostEntry myHost = new IPHostEntry();

                myHost = Dns.GetHostEntry(this.textBox1.Text);
                for (int i = 0; i < myHost.AddressList.Length; i++)
                {
                    this.textBox2.Text = myHost.AddressList[i].ToString();
                }
            }
        }
    }
}