using System;

using System.Globalization;

​

namespace Rextester

{

    public class Program

    {

        public static bool TryParseArchiveDate(string dateStringFromArchive)

        {

            DateTime dateTime;

            var acceptedFormats = new[]{

                "yyyy-MM-dd", // Pure date

                "yyyy-MM-ddTHH:mm:ss", // date + time

                "yyyy-MM-ddTHH:mm:ss.FFFFFFFK" // date + time + milliseconds + timezone

            };

            DateTime.TryParseExact(dateStringFromArchive, acceptedFormats, CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind, out dateTime);

            Console.WriteLine(dateTime.ToString("dd.MM.yyyy, HH:mm"));

            return true;

        }

​

        public static void Main(string[] args)

        {

            TryParseArchiveDate("2009-03-31T18:05:18+02:00");

            TryParseArchiveDate("2009-03-31T18:05:18.000Z");

            TryParseArchiveDate("2009-03-31T18:05:18.9001");

        }

    }

}