LINQ. Sample. Sort list of IP addresses

In file “list.txt” I have one-per-line list of IP addresses that I’d like to sort.

I understand that it’s possible to do in many different ways.

But I’d like to illustrate use of LINQ for this.

Function to calculate decimal presentation of IP address:
private Int64 Ip2Decimal(String ip)

{

    String[] d;

    Int64 iRes = -1;

    try {

        d = ip.Split('.');

        iRes = Int64.Parse(d[3]) + 256 * (Int64.Parse(d[2]) + 256 *

              (Int64.Parse(d[1]) + 256 * Int64.Parse(d[0])));

    }

    catch (Exception) {}

    return iRes;

}
Read unordered list and write the sorted one:
// file "list.txt" contains one-per-line IP address

StreamReader sr = new StreamReader("list.txt");
String txtIp = sr.ReadToEnd();
sr.Close();

// dictionary with key=IpAddress, value={decimal presentation}

Dictionary<String, Int64> listIP = new Dictionary<String, Int64>();

String[] arr = txtIp.Split(Environment.NewLine.ToCharArray());

foreach (String strIP in arr)

{

    if (strIP.Length > 0 && !listIP.ContainsKey(strIP))

    {

        listIP.Add(strIP, Ip2Decimal(strIP));

    }

}

var orderedIpList = from ip in listIP

                    orderby ip.Value

                    select ip.Key;

String[] orderedArr=orderedIpList.ToArray();

StreamWriter sw = new StreamWriter("orderedList.txt");

txtIp = String.Join(Environment.NewLine, orderedArr);

sw.Write(txtIp);

sw.Close();