Best way to retrieve accurate date?

Question

What is the best way to retrieve the current date? Currently I am storing the date like this:

string date = DateTime.Now.ToString("yyyyMMdd");

Obviously, if the user changes the date on their system, this will also be affected.

I need a way to access an accurate date (preferable in central time) and store it as a string within my application. Any ideas?

Answer 1

Define "accurate"? If you cannot trust the system date, then you need to get the time from an outside source (ie, atomic clock). But the user may block your program from getting it (ie, unplugging the network cable, blocking your time query with a software firewall).

So what is it that you really want?

Answer 2

EDIT: This works, give it a try:

private string GetCurrentDateTime()
{
    WebRequest request = WebRequest.Create(@"http://developer.yahooapis.com/TimeService/V1/getTime?appid=Test");
    // request.Proxy = new WebProxy("PROXYSERVERNAME", 8080); // You may or may not need this
    WebResponse response = request.GetResponse();      

    Double currentTimeStamp = 0;
    using (Stream stream = response.GetResponseStream())
    {
        using (XmlTextReader xmlReader = new XmlTextReader(stream))
        {
            while (xmlReader.Read())
            {
                switch (xmlReader.NodeType)
                {
                    case XmlNodeType.Element:
                        if (xmlReader.Name == "Timestamp")
                        {
                            currentTimeStamp = Convert.ToDouble(xmlReader.ReadInnerXml());
                        }
                        break;
                }
            }

            xmlReader.Close();
        }
    }

    DateTime yahooDateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0);
    return yahooDateTime.AddSeconds(currentTimeStamp).AddHours(2).ToString("yyyyMMdd");     
}