1、using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Net.NetworkInformation;

namespace 判断是否联网

{

class Program

{

static void Main(string[] args)

{

Ping p = new Ping();

PingReply pr;

pr = p.Send("119.75.218.45");//百度的IP

if (pr.Status != IPStatus.Success)//如果连接不成功

{

Console.WriteLine("未联网");

}

else

{

Console.WriteLine("已联网");

}

Console.Read();

}

}

}

2、

  WebRequest myrequest = WebRequest.Create("http://www.baidu.com");

            WebResponse myres = null;

            try

            {

                myres = myrequest.GetResponse();

                myres.Close();

                MessageBox.Show("连上了");

            }

            catch (Exception)

            {

                MessageBox.Show("连不上了");

            }

 

3、

public partial class Form1 : Form

{

        //判断网络连接

        [DllImport("wininet")]

        private extern static bool InternetGetConnectedState(out int connectionDescription, int reservedValue);

        ///<summary>

        /// 检测本机的网络连接

        ///</summary>

 

       private void button1_Click(object sender, EventArgs e)

        {

            //判断是否联网

                int i = 0;

                if (InternetGetConnectedState(out i, 0))

                {

                    //联网

                    MessageBox.Show("Thylx提醒您：你的计算机已连接到网络上！");

                 }

                 else

                  {

                     //断网

                     MessageBox.Show("Thylx提醒您：本地连接已断开！");

                  }

        }

}