DateTime dt = DateTime.Now; //当前时间 DateTimestartWeek = dt.AddDays(1 -Convert.ToInt32(dt.DayOfWeek.ToString("d"))); //本周周一 DateTimeendWeek = startWeek.AddDays(6); //本周周日 DateTimestartMonth = dt.AddDays(1 - dt.Day); //本月月初 DateTimeendMonth = startMonth.AddMonths(1).AddDays(-1); //本月月末 //DateTimeendMonth = startMonth.AddDays((dt.AddMonths(1) - dt).Days - 1); //本月月末 DateTimestartQuarter = dt.AddMonths(0 - (dt.Month - 1) % 3).AddDays(1 -dt.Day); //本季度初 DateTimeendQuarter = startQuarter.AddMonths(3).AddDays(-1); //本季度末 DateTimestartYear = new DateTime(dt.Year, 1, 1); //本年年初 DateTimeendYear = new DateTime(dt.Year, 12, 31); //本年年末 //提取当前日期为星期几 string[] Day =new string[] { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"}; string week =Day[Convert.ToInt32(DateTime.Now.DayOfWeek.ToString("d"))].ToString(); //星期五 DateTime.Now.DayOfWeek.ToString(); //英文星期显示,Friday (int)DateTime.Now.DayOfWeek // 数字,若是周五,结果对应为5 DateTime.Now.ToString("dddd", newSystem.Globalization.CultureInfo("zh-cn")); //星期五 DateTime.Now.ToString("dddd"); //星期五 DateTime.Now.ToString("dddd,MMMM,dd ,yyyy",newSystem.Globalization.DateTimeFormatInfo()); //显示日期格式:Friday,November,30,2012 DateTime.Now.ToString("dddd,dd MMMM,yyyy"); //星期五,30 十一月,2012 //上周,同理,一个周是7天,上周就是本周再减去7天,下周也是一样 DateTime.Now.AddDays(Convert.ToInt32(1 -Convert.ToInt32(DateTime.Now.DayOfWeek)) - 7); //上周一 DateTime.Now.AddDays(Convert.ToInt32(1 -Convert.ToInt32(DateTime.Now.DayOfWeek)) - 7).AddDays(6); //上周末(星期日) //下周 DateTime.Now.AddDays(Convert.ToInt32(1 -Convert.ToInt32(DateTime.Now.DayOfWeek)) + 7); //下周一 DateTime.Now.AddDays(Convert.ToInt32(1 -Convert.ToInt32(DateTime.Now.DayOfWeek)) + 7).AddDays(6);//下周末 //本月,很多人都会说本月的第一天嘛肯定是1号,最后一天就是下个月一号再减一天。当然这是对的 //一般的写法 DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() +"1"; //第一天 DateTime.Parse(DateTime.Now.Year.ToString() +DateTime.Now.Month.ToString() +"1").AddMonths(1).AddDays(-1).ToShortDateString();//最后一天 //巧用C#里ToString的字符格式化更简便 DateTime.Now.ToString("yyyy-MM-01"); DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).AddDays(-1).ToShortDateString(); //上个月,减去一个月份 DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(-1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString(); //下个月,加去一个月份 DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(2).AddDays(-1).ToShortDateString(); //7天后 DateTime.Now.Date.ToShortDateString(); DateTime.Now.AddDays(7).ToShortDateString(); //7天前 DateTime.Now.AddDays(-7).ToShortDateString(); DateTime.Now.Date.ToShortDateString(); //本年度,用ToString的字符格式化我们也很容易地算出本年度的第一天和最后一天 DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(1).AddDays(-1).ToShortDateString(); //上年度,不用再解释了吧 DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(-1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddDays(-1).ToShortDateString(); //下年度 DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(2).AddDays(-1).ToShortDateString(); //本季度,很多人都会觉得这里难点,需要写个长长的过程来判断。其实不用的,我们都知道一年四个季度,一个季度三个月 //首先我们先把日期推到本季度第一个月,然后这个月的第一天就是本季度的第一天了 DateTime.Now.AddMonths(0 - ((DateTime.Now.Month - 1) %3)).AddDays(1 - DateTime.Now.Day); //同理,本季度的最后一天就是下季度的第一天减一 DateTime.Parse(DateTime.Now.AddMonths(3 - ((DateTime.Now.Month- 1) %3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString(); //下季度 DateTime.Now.AddMonths(3 - ((DateTime.Now.Month - 1) %3)).ToString("yyyy-MM-01"); DateTime.Parse(DateTime.Now.AddMonths(6 - ((DateTime.Now.Month- 1) %3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString(); //上季度 DateTime.Now.AddMonths(-3 - ((DateTime.Now.Month - 1) % 3)).AddDays(1 - DateTime.Now); DateTime.Now.AddMonths(0 - ((DateTime.Now.Month - 1) %3)).AddDays(1 -DateTime.Now.Day).AddDays(-1).ToShortDateString();
https://www.cnblogs.com/amylis_chen/p/6929301.html