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  • 【转载】对C#DateTime的一些扩展,计算周内第一天,最后一天

        /// <summary>
        /// DateTime的一些扩展
        /// </summary>
        public class DateTime2
        {
            /// <summary>
            /// 得到本周第一天(以星期天为第一天)
            /// </summary>
            /// <param name="datetime"></param>
            /// <returns></returns>
            public DateTime GetWeekFirstDaySun(DateTime datetime)
            {
                //星期天为第一天
                int weeknow = Convert.ToInt32(datetime.DayOfWeek);
                int daydiff = (-1) * weeknow;
    
                //本周第一天
                string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
                return Convert.ToDateTime(FirstDay);
            }
    
            /// <summary>
            /// 得到本周第一天(以星期一为第一天)
            /// </summary>
            /// <param name="datetime"></param>
            /// <returns></returns>
            public DateTime GetWeekFirstDayMon(DateTime datetime)
            {
                //星期一为第一天
                int weeknow = Convert.ToInt32(datetime.DayOfWeek);
    
                //因为是以星期一为第一天,所以要判断weeknow等于0时,要向前推6天。
                weeknow = (weeknow == 0 ? (7 - 1) : (weeknow - 1));
                int daydiff = (-1) * weeknow;
    
                //本周第一天
                string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
                return Convert.ToDateTime(FirstDay);
            }
    
            /// <summary>
            /// 得到本周最后一天(以星期六为最后一天)
            /// </summary>
            /// <param name="datetime"></param>
            /// <returns></returns>
            public DateTime GetWeekLastDaySat(DateTime datetime)
            {
                //星期六为最后一天
                int weeknow = Convert.ToInt32(datetime.DayOfWeek);
                int daydiff = (7 - weeknow) - 1;
    
                //本周最后一天
                string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
                return Convert.ToDateTime(LastDay);
            }
    
            /// <summary>
            /// 得到本周最后一天(以星期天为最后一天)
            /// </summary>
            /// <param name="datetime"></param>
            /// <returns></returns>
            public DateTime GetWeekLastDaySun(DateTime datetime)
            {
                //星期天为最后一天
                int weeknow = Convert.ToInt32(datetime.DayOfWeek);
                weeknow = (weeknow == 0 ? 7 : weeknow);
                int daydiff = (7 - weeknow);
    
                //本周最后一天
                string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
                return Convert.ToDateTime(LastDay);
            }
        }

    原文链接:http://blog.csdn.net/joyhen/article/details/9179763

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  • 原文地址:https://www.cnblogs.com/baiyunchen/p/4811947.html
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