C# 时间对比

        public bool IfTime(string StartTime, string EndTime)
        {
            DateTime dt1 = Convert.ToDateTime(StartTime);
            DateTime dt2 = Convert.ToDateTime(EndTime);
            if (DateTime.Compare(dt1, dt2) < )
            {
                //开始时间 < 结束时间 (执行以下语句),,说明开始时间晚
                return true;
            }
            return false;
        }

starttime= DateTime.Now.ToShortTimeString().ToString();

public int Time_Minute_diff(string StartTime, string EndTime)
{
DateTime dt1 = Convert.ToDateTime(StartTime);
DateTime dt2 = Convert.ToDateTime(EndTime);
return dt1.Minute - dt2.Minute;
}

 /// <summary>
        /// 获得固定年月日,时和分不固定 : 2019-01-01 00:00:00
        /// </summary>
        /// <returns></returns>
        public DateTime GetFixedDateTime()
        {
            string time1 = DateTime.Now.ToShortTimeString(); //16:50
            //yyyy-MM-dd hh:mm:ss //2019-01-01 16:34:00
            string Ymd = "2019-01-01 ";
            string Hour = DateTime.Now.Hour.ToString();
            string Minute = DateTime.Now.Minute.ToString();
            return Convert.ToDateTime(Ymd + Hour + ":" + Minute + ":" + 00);
        }

        /// <summary>
        /// 获得固定年月日,时和分不固定 : 2019-01-01 00:00:00
        /// </summary>
        /// <returns></returns>
        public DateTime GetFixedDateTime(string Hour = "", string Minute = "")
        {
            string time1 = DateTime.Now.ToShortTimeString(); //16:50
            //yyyy-MM-dd hh:mm:ss //2019-01-01 16:34:00
            string Ymd = "2019-01-01 ";
            if (Hour == "")
            {
                Hour = DateTime.Now.Hour.ToString();
                Minute = DateTime.Now.Minute.ToString();
            }
            return Convert.ToDateTime(Ymd + Hour + ":" + Minute + ":" + 00);
        }