C#獲取時(shí)間，日期

//C#里內(nèi)置的DateTime基本上都可以實(shí)現(xiàn)這些功能，巧用DateTime會(huì)使你處理這些事來(lái)變輕松多了
????? //今天
???????????????? DateTime.Now.Date.ToShortDateString();
??? //昨天，就是今天的日期減一
???????????????? DateTime.Now.AddDays(-1).ToShortDateString();
??? //明天，同理，加一
???????????????? DateTime.Now.AddDays(1).ToShortDateString();

????? //本周(要知道本周的第一天就得先知道今天是星期幾，從而得知本周的第一天就是幾天前的那一天，要注意的是這里的每一周是從周日始至周六止
???????????????? DateTime.Now.AddDays(Convert.ToDouble((0 - Convert.ToInt16(DateTime.Now.DayOfWeek)))).ToShortDateString();
???????????????? DateTime.Now.AddDays(Convert.ToDouble((6 - Convert.ToInt16(DateTime.Now.DayOfWeek)))).ToShortDateString();
????? //如果你還不明白，再看一下中文顯示星期幾的方法就應(yīng)該懂了
? //由于DayOfWeek返回的是數(shù)字的星期幾，我們要把它轉(zhuǎn)換成漢字方便我們閱讀，有些人可能會(huì)用switch來(lái)一個(gè)一個(gè)地對(duì)照，其實(shí)不用那么麻煩的?????????????
?? ?????????????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" };
???????????????? Day[Convert.ToInt16(DateTime.Now.DayOfWeek)];

? //上周，同理，一個(gè)周是7天，上周就是本周再減去7天，下周也是一樣
DateTime.Now.AddDays(Convert.ToDouble((0 - Convert.ToInt16(DateTime.Now.DayOfWeek)))-7).ToShortDateString();
DateTime.Now.AddDays(Convert.ToDouble((6 - Convert.ToInt16(DateTime.Now.DayOfWeek)))-7).ToShortDateString();
? //下周
DateTime.Now.AddDays(Convert.ToDouble((0 - Convert.ToInt16(DateTime.Now.DayOfWeek)))+7).ToShortDateString();
DateTime.Now.AddDays(Convert.ToDouble((6 - Convert.ToInt16(DateTime.Now.DayOfWeek)))+7).ToShortDateString();
??//本月,很多人都會(huì)說(shuō)本月的第一天嘛肯定是1號(hào)，最后一天就是下個(gè)月一號(hào)再減一天。當(dāng)然這是對(duì)的
? //一般的寫法
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的字符格式化更簡(jiǎn)便
???????????????? DateTime.Now.ToString("yyyy-MM-01");
???????????????? DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).AddDays(-1).ToShortDateString();

? //上個(gè)月，減去一個(gè)月份
???????????????? DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(-1).ToShortDateString();
???????????????? DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
? //下個(gè)月，加去一個(gè)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的字符格式化我們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，不用再解釋了吧
???????????????? 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，很多人都會(huì)覺(jué)得這里難點(diǎn)，需要寫個(gè)長(zhǎng)長(zhǎng)的過(guò)程來(lái)判斷。其實(shí)不用的，我們都知道一年四個(gè)季度，一個(gè)季度三個(gè)月
? //首先我們先把日期推到本季度第一個(gè)月，然后這個(gè)月的第一天就是本季度的第一天了
???????????????? DateTime.Now.AddMonths(0 - ((DateTime.Now.Month- 1)% 3)).ToString("yyyy-MM-01");
? //同理，本季度的最后一天就是下季度的第一天減一
???????????????? DateTime.Parse(DateTime.Now.AddMonths(3 - ((DateTime.Now.Month- 1)% 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
? //下季度，相信你們都知道了。。。。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)).ToString("yyyy-MM-01");
???????????????? DateTime.Parse(DateTime.Now.AddMonths(0 - ((DateTime.Now.Month- 1)% 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();

c#中如何獲取時(shí)間！1、DateTime 數(shù)字型
?System.DateTime currentTime=new System.DateTime();

C#如何獲得系統(tǒng)時(shí)間