public static class DateHelp

    {

        /// <summary>

        /// 获取当前日期是该月的第几周

        /// </summary>

        /// <param name="dateNow"></param>

        /// <returns>该日期所在周是第几周</returns>

        public static int WeekOfMonth(DateTime dateNow)

        {

            DateTime StartDate = new DateTime(dateNow.Year, dateNow.Month, );

            DateTime EndDate = StartDate.AddMonths().AddDays(-);

            int WeekIndex = ;

            TimeSpan ts = dateNow - StartDate;

            DateTime TempDate = StartDate;

            if (TempDate.DayOfWeek == System.DayOfWeek.Monday)

                TempDate = TempDate.AddDays();

            while (TempDate <= EndDate)

            {

                if (TempDate.DayOfWeek == System.DayOfWeek.Monday && dateNow.ToString("yyyy-MM-dd") != StartDate.ToString("yyyy-MM-dd"))

                {

                    WeekIndex++;

                }

                if (TempDate.ToString("yyyy-MM-dd") == dateNow.ToString("yyyy-MM-dd"))

                {

                    break;

                }

                TempDate = TempDate.AddDays();

            }

            return WeekIndex;

        }

        /// <summary>

        /// 获取当前日期所在周的周一日期

        /// </summary>

        /// <param name="dateNow"></param>

        /// <returns></returns>

        public static DateTime? GetStartWeekDate(DateTime dateNow)

        {

            for (int i = ; i < ; i++)

            {

                DateTime temp = dateNow.AddDays(i * (-));

                if (temp.DayOfWeek == System.DayOfWeek.Monday)

                    return temp;

            }

            return null;

        }

        /// <summary>

        /// 获取当前日期所在周的周日日期

        /// </summary>

        /// <param name="dateNow"></param>

        /// <returns></returns>

        public static DateTime? GetEndWeekDate(DateTime dateNow)

        {

            for (int i = ; i < ; i++)

            {

                DateTime temp = dateNow.AddDays(i);

                if (temp.DayOfWeek == System.DayOfWeek.Sunday)

                    return temp;

            }

            return null;

        }

    }