C#将ip地址转换成长整形数字

这段代码可以将点分隔的ip地址转换成长整形数字，非常实用

public static long ConvertIPToLong(string ipAddress)
{
    // code from http://www.75271.com
    System.Net.IPAddress ip;

    if (System.Net.IPAddress.TryParse(ipAddress, out ip))
    {
        byte[] bytes = ip.GetAddressBytes();

        return (long)
            (
            16777216 * (long)bytes[0] +
            65536 * (long)bytes[1] +
            256 * (long)bytes[2] +
            (long)bytes[3]
            )
            ;
    }
    else
        return 0;
}