C# 获取某月的第一天和最后一天

来源：互联网发布：软件系统接口设计方案编辑：程序博客网时间：2024/05/20 21:22

/// <summary>
        /// 取得某月的第一天
        /// </summary>
        /// <param name="datetime">要取得月份第一天的时间</param>
        /// <returns></returns>
        private DateTime FirstDayOfMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day);
        }

        //// <summary>
        /// 取得某月的最后一天
        /// </summary>
        /// <param name="datetime">要取得月份最后一天的时间</param>
        /// <returns></returns>
        private DateTime LastDayOfMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day).AddMonths(1).AddDays(-1);
        }

        //// <summary>
        /// 取得上个月第一天
        /// </summary>
        /// <param name="datetime">要取得上个月第一天的当前时间</param>
        /// <returns></returns>
        private DateTime FirstDayOfPreviousMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day).AddMonths(-1);
        }

        //// <summary>
        /// 取得上个月的最后一天
         /// </summary>
        /// <param name="datetime">要取得上个月最后一天的当前时间</param>
        /// <returns></returns>
        private DateTime LastDayOfPrdviousMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day).AddDays(-1);

}

/// 获取指定日期，在为一年中为第几周

/// <param name="dt">指定时间</param>

/// <reutrn>返回第几周</reutrn>

private static int GetWeekOfYear(DateTime dt){

GregorianCalendar gc = new GregorianCalendar();

int weekOfYear = gc.GetWeekOfYear(dt,CalendarWeekRule.FirstDay, DayOfWeek.Monday);

return weekOfYear;}

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