.net日期类与UNIX时间戳的相互转换，长数字

第一种

//将系统时间转换成unix时间戳
        public string timeunix(string time)
        {
            DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
            DateTime dtNow = DateTime.Parse(DateTime.Now.ToString());
            TimeSpan toNow = dtNow.Subtract(dtStart);
            string timeStamp = toNow.Ticks.ToString();
            timeStamp = timeStamp.Substring(0, timeStamp.Length - 7);
            return timeStamp;
        }
        //将unix时间戳转换成系统时间
        public DateTime unixtime(string time)
        {
            DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
            long lTime = long.Parse(time + "0000000");
            TimeSpan toNow = new TimeSpan(lTime);
            DateTime dtResult = dtStart.Add(toNow);
            return dtResult;
        }

第二种

        //将系统时间转换成unix时间戳
        public static long timeunix(DateTime dt)
        {
            DateTimeOffset dto = new DateTimeOffset(dt);
            return dto.ToUnixTimeSeconds();
        }

        //将系统时间转换成unix时间戳
        public static DateTime unixtime(double d)
        {
            System.DateTime time = System.DateTime.MinValue;
            System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));
            time = startTime.AddMilliseconds(d);
            return time;
        }