[this code segment was partly copy from somewhere else, Not my own article] 

         public long DateTime2UnixTimeStamp(DateTime dt)
        {
            DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
            DateTime dtNow = DateTime.Parse(dt.ToString());
            TimeSpan toNow = dtNow.Subtract(dtStart);
            string timeStamp = toNow.Ticks.ToString();
            timeStamp = timeStamp.Substring(0, timeStamp.Length - 7);

            return Convert.ToInt64(timeStamp);
        }

        public DateTime UnixTimeStamp2DateTime(long uts)
        {
            DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
            long lTime = long.Parse(uts.ToString() + "0000000");
            TimeSpan toNow = new TimeSpan(lTime);
            DateTime dtResult = dtStart.Add(toNow);

            return dtResult;
        }