【C#日期系列（三）】--C#获取某个月的第一个星期几的年月日

需要获取某个月的第一个星期几的年月日

简单写了一个算法

#region 计算每月第一个星期1-7是各是几号
        /// <summary>
        /// 计算每月第一个星期1-7是各是几号
        /// </summary>
        /// <param name="monthStratTime"></param>
        /// <param name="calcWeek">DayOfWeek枚举 注意周日枚举为0</param>
        /// <returns></returns>
        public static DateTime GetEachMonthFirstWeek(DateTime monthStratTime, DayOfWeek calcWeek)
        {
            DayOfWeek week = monthStratTime.DayOfWeek;//第一天是星期几
            int result = 0;
            if (calcWeek == DayOfWeek.Sunday)
            {
                result = (8 - (int)week) % 7 + 7;
            }
            else
            {
                result = (8 - (int)week) % 7 + (int)calcWeek;
            }

            if (result > 7)
            {
                result = result - 7;
            }
            monthStratTime = monthStratTime.AddDays(result-1);
            return monthStratTime;
        }
        #endregion