public double Dot2LongIP(string DottedIP)
{
    int i;
    string [] arrDec;
    double num = 0;
    if (DottedIP == "")
    {
       return 0;
    }
    else
    {
       arrDec = DottedIP.Split('.');
       for(i = arrDec.Length - 1; i >= 0 ; i --)
       {
          num += ((int.Parse(arrDec[i])%256) * Math.Pow(256 ,(3 - i )));
       }
       return num;
    }
}