计算某个日期为星期几

使用基姆拉尔森计算公式

        /// <summary>
        /// 计算某个日期为星期几
        /// </summary>
        /// <param name="year">年</param>
        /// <param name="month">月</param>
        /// <param name="day">日</param>
        /// <returns>星期几</returns>
        public static string CaculateWeekDay(int year, int month, int day)
        {
            if (month == 1 || month == 2)
            {
                month += 12;
                year--;
            }
            int week = (day + 2 * month + 3 * (month + 1) / 5 + year + year / 4 - year / 100 + year / 400 + 1) % 7;
            string weekstr = "";
            switch (week)
            {
                case 1: weekstr = "星期一"; break;
                case 2: weekstr = "星期二"; break;
                case 3: weekstr = "星期三"; break;
                case 4: weekstr = "星期四"; break;
                case 5: weekstr = "星期五"; break;
                case 6: weekstr = "星期六"; break;
                case 7: weekstr = "星期七"; break;

            }
          return  weekstr;
        }