根據年份和月份獲得天數

        /// <summary>
        /// 根據年份與月份獲取天數
        /// </summary>
        /// <param name="year">年份</param>
        /// <param name="month">月份</param>
        /// <returns>當月的天數</returns>
        private int GetDayNumber(int year, int month)
        {
            int[] days = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
            if (2 == month && 0 == (year % 4) && (0 != (year % 100) || 0 == (year % 100)))
                days[1] = 29;
            return days[month - 1];
        }