using System;

public class Program

{

    public static void Main()

    {

        string IP ="5.23.123.12";

        Console.WriteLine( ip_to_number(IP).ToString() );

    }

    public static long ip_to_number(string ip_addr)

      {

          string[] ip_Sblock;

          int[] ip_block = new int[4];

          string[] separator = { "." };

​

          ip_Sblock = ip_addr.Split(separator, StringSplitOptions.None);

          for (int i = 0; i <= 3; i++)

          {

              ip_block[i] = Convert.ToInt32(ip_Sblock[i]);

          }

​

          return ip_block[0] * 16777216 + ip_block[1] * 65536 + ip_block[2] * 256 + ip_block[3];

      }

}

​

​