Learning System.Net 001

1.Creating an instance of IPAddress (using System.Net; is required)

IPAddress ipAddress = IPAddress.Parse("192.168.0.99");

youknow,”192.168.0.99” is an ip address string,this is right

but,if you use “www.baidu.com”,or even “localhost”,a FormatException occurs.

so a nicer design should be:

            try
            {

                //wrong
                IPAddress ipAddress = IPAddress.Parse("localhost");
            }
            catch (FormatException ex)
            {

                //the alert text should be “指定了无效的 IP 地址”
                MessageBox.Show(ex.Message);
            }

2.using Dns

<1>get the host name:

string strLocalHostName  = Dns.GetHostName();

<2>

//obviously,this synatx is obsoleted

IPHostEntry ipHostEntry = Dns.Resove(“www.microsoft.com”);

//we’d better use this

IPHostEntry ipHostEntry = Dns.GetHostEntry(“www.microsoft.com”);

<3>

foreach(IPAddress ip in ipHostEntry.AddressList)

{

    Show(ip.ToString());

}

generally speaking the ipHostEntry.AddressList[0],will be the one will usually need.