Calculating the broadcast address for a subnet

Introduction

This code returns the subnet broadcast address for a given IP address and subnet mask.

I needed it for a WOL function on a website which was in a different subnet and where the standard broadcast address didn't work.

Using the code

This function is quite easy, and could be used, for example, in an UdpClient object, like this:

UdpClient client = new UdpClient();
client.Connect(CalculateBroadCastAddress(ip,nm).ToString(), 40000);

Here is the complete source code:

using System.Net.Sockets;
using System.Net;
using System.Globalization;
using System.Collections;

           
static IPAddress CalculateBroadCastAddress(IPAddress currentIP, IPAddress ipNetMask)
{
    string[] strCurrentIP = currentIP.ToString().Split('.');
    string[] strIPNetMask = ipNetMask.ToString().Split('.');

    ArrayList arBroadCast = new ArrayList();

    for (int i = 0; i < 4; i++)
    {
        int nrBCOct = int.Parse(strCurrentIP[i]) | (int.Parse(strIPNetMask[i]) ^ 255);
        arBroadCast.Add(nrBCOct.ToString());
    }
    return IPAddress.Parse(arBroadCast[0] + "." + arBroadCast[1] + 
           "." + arBroadCast[2] + "." + arBroadCast[3]);
}