DateTime dt = DateTime.Now
DateTime startWeek = dt.AddDays(1 - Convert.ToInt32(dt.DayOfWeek.ToString("d")))
DateTime endWeek = startWeek.AddDays(6)
DateTime startMonth = dt.AddDays(1 - dt.Day)
DateTime endMonth = startMonth.AddMonths(1).AddDays(-1)
//DateTime endMonth = startMonth.AddDays((dt.AddMonths(1) - dt).Days - 1)
DateTime startQuarter = dt.AddMonths(0 - (dt.Month - 1) % 3).AddDays(1 - dt.Day)
DateTime endQuarter = startQuarter.AddMonths(3).AddDays(-1)
DateTime startYear = new DateTime(dt.Year, 1, 1)
DateTime endYear = new DateTime(dt.Year, 12, 31)
至于昨天、明天、上周、上月、上季度、上年度等等,只要AddDays()、AddMonths()、AddYears()这几种方法组合一下就可以了。
C#中datetime的使用
//如果你还不明白,再看一下中文显示星期几的方法就应该懂了
//由于DayOfWeek返回的是数字的星期几,我们要把它转换成汉字方便我们阅读,有些人可能会用switch来一个一个地对照,其实不用那么麻烦的
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()
//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)
DateTime.Now.AddDays(Convert.ToInt32 (1 - Convert.ToInt32(DateTime.Now.DayOfWeek)) - 7).AddDays(6)
//下周
DateTime.Now.AddDays(Convert.ToInt32 (1 - Convert.ToInt32(DateTime.Now.DayOfWeek)) + 7)
DateTime.Now.AddDays(Convert.ToInt32(1 - Convert.ToInt32(DateTime.Now.DayOfWeek)) + 7).AddDays(6)
//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"
DateTime.Parse(DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + "1").AddMonths(1).AddDays(-1).ToShortDateString()
//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,相信你们都知道了。。。。收工
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()