C# 判断系统是否连接网络

 public partial class Form1 : Form     {

 [DllImport("wininet.dll")]

private extern static bool getInterState(out int conn, int val);

 public Form1()  

{       

  InitializeComponent();  

           getNet();     

    }        

//判断当前是否连接入Internet网络

  private void getNet()

  {  

           int Out;

            if (getInterState(out Out, 0) == true)

             {  

               label1.Text = " 网络已连接！";  

               }    

         else

            {  

               label1.Text = " 网络未成功连接！";                          

             }        

    }            

}