C#

public static IEnumerable<IPAddress> ParseIPAddressRange(string inputString)
{
  string[] tokens = inputString.Split('.');
  foreach (IPAddress addr in ParseIPAddressRange(tokens, 0, string.Empty))
    yield return addr;
}
private static IEnumerable<IPAddress> ParseIPAddressRange(string[] tokens, int index, string partial)
{
  if (index > 3)
    yield return IPAddress.Parse(partial);
  else if (index >= tokens.Length || tokens[index] == "*")
  {
    for (int x = 0; x < 256; x++)
      foreach (IPAddress addr in ParseIPAddressRange(tokens, index + 1, partial + "." + x.ToString()))
        yield return addr;
  }
  else
  {
    // Parse out tokens[index], append it to partial and recurse like above
    // This is just an exercise in string parsing... Easy.
  }
}

foreach (string component in tokens[index].Split(','))
{
  if (component.Contains('-'))
  {
    string[] range = component.Split('-');
    if (range.Length != 2) throw new ArgumentException();
    int startRange, endRange;
    if (int.TryParse(range[0], out startRange) && int.TryParse(range[1], out endRange) && startRange <= endRange)
      for (int x = startRange; x <= endRange; x++)
        foreach (IPAddress addr in ParseIPAddressRange(tokens, index + 1, partial + "." + x.ToString()))
          yield return addr;
    else
      throw new ArgumentException();
  }
  else if (component.Contains('/')
  {
    // You should really be able to figure out the /xx notation on your own, given the above block.
  }
}

DateTime dt1 = new DateTime(2011, 11, 12);
DateTime dt2 = new DateTime(2011, 11, 13);
DateTime dt3 = new DateTime(2011, 11, 14);
DateTime dt4 = new DateTime(2011, 11, 15);
Console.WriteLine(dt4.Subtract(dt4).Days);
Console.WriteLine(dt4.Subtract(dt3).Days);
Console.WriteLine(dt4.Subtract(dt2).Days);
Console.WriteLine(dt4.Subtract(dt1).Days);

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OriginalGriff wrote:

So where do you think it is I am making a mistake?