得到时间段内周末的天数

        /// <summary>
        /// 得到一个时间段内周末的天数
        /// </summary>
        /// <param name="stDate">开始时间</param>
        /// <param name="endDate">结束时间</param>
        /// <returns></returns>
        public double GetWeekEndTotalDays(DateTime stDate,DateTime endDate)
        {
            double weekEndCount = 0.000;

            if (endDate.Date.ToString() == stDate.Date.ToString() &&
                (stDate.DayOfWeek.ToString() == "Saturday" || stDate.DayOfWeek.ToString() == "Sunday"))
            {
                weekEndCount += (endDate - stDate).TotalDays;
                return weekEndCount;
            }

            //计算不在活动范围内的周末的天数
            if (stDate.DayOfWeek.ToString() == "Saturday" || stDate.DayOfWeek.ToString() == "Sunday")
                weekEndCount += (stDate.AddDays(1).Date - stDate).TotalDays;
            stDate = stDate.AddDays(1).Date;
            if (endDate.DayOfWeek.ToString() == "Saturday" || endDate.DayOfWeek.ToString() == "Sunday")
                weekEndCount += (endDate - endDate.AddDays(-1).Date).TotalDays;
            endDate = endDate.AddDays(-1).Date;

            TimeSpan tsWeekEnd = endDate - stDate;
            for (int j = 0; j <= tsWeekEnd.Days; j++)
            {
                if (stDate.DayOfWeek.ToString() == "Saturday" || stDate.DayOfWeek.ToString() == "Sunday")
                {
                    weekEndCount += 1;
                }
            }
            return weekEndCount;
        }