C#获取本地IP地址兼容win7和xp

获取本机ip本来是很容易的，IPAddress _ip = Dns.GetHostAddresses(Dns.GetHostName())[0];就行了

但是在vista win7等系统里面这样获得的是ipv6地址，

 private string GetLocalIp()
 {
    string localIp;
    IPHostEntry host;
    host = Dns.GetHostEntry(Dns.GetHostName());
    if (host.AddressList.Length > 1)
    {
       //win7 ip 这里或许要用length
       localIp = host.AddressList[1].ToString();
    }
    else
    {
       //xp
       localIp = host.AddressList[0].ToString();
    }

    return localIp;

 }