C#时间

//今天   
DateTime.Now.Date.ToShortDateString();   
//昨天,也就是今天的日期减一   
DateTime.Now.AddDays(-1).ToShortDateString();   
//明天,同理,加一   
DateTime.Now.AddDays(1).ToShortDateString();   
//本周(要知道本周第一天就得先知道今天是星期几,从而得知   
本周第一天就是几天前的那一天;每一周是从周日始至周六止[0-6])   
DateTime.Now.AddDays(Convert.ToDouble((0-Convert.ToInt16   
(DateTime.Now.DayOfWeek)))).ToShortDateString();   
   //DateTime.Now.DayOfWeek获得今天是本周的第几天(0<=n<=6)   
DateTime.Now.AddDays(Convert.ToDouble((6-Convert.ToInt16   
(DateTime.Now.DayOfWeek)))).ToShortDateString();   
//中文显示星期几   
//由于DayOfWeek返回的是数字的星期几,需要把它转换成汉字以方便人们   
阅读,有些人会用SWITCH来一个一个地对照,其实我们有更优的策略   
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)];//使用它来获取   
//上周,同理,一个周是7天,上周就是本周在减去7天,下周也是一样   
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,本月的第一天是1号,最后一天就是下个月的1号再减一天   
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,加上一个月份   
DateTime.Parse(Datetime.Now.ToString("yyyy-MM-01")).AddMonths(1).ToShortDateString();   
DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(2).AddDays(-1).ToShortString();   
//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).ToShortString();   
//上年度   
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是难点,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)).ToString("yyyy-MM-01");   
//同理,本季度的最后一天就是下个季度的第一天减一   
DateTime.Parse.(DateTime.Now.AddMonth(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)).ToString("yyyy-MM-01");   
DateTime.Parse(DateTime.Now.AddMonths(0-((DateTime.Now.Month-1)%3)).ToString("yyyy-MM-01").AddDays(-1).ToShortDateString();   
//获得当月有多少天   
int m=System.DateTime.DaysInMonth(System.DateTime.Now.Year,System.DateTime.Now.Month);   
//获取某月的实际工作日(即不包括周六日)   
//int days=getDays(System.DateTime.Now);调用即可获得   
private int getDays(System.DateTime date1)   
{   
int m=System.DateTime.DaysInMonth(date1.Year,date1.Month);   
int mm=0;   
for(int i=1;i<=m;i++)   
{   
System.DateTime date=Convert.ToDateTime(date1.Year+"-"+date1.Month+"-"+i);   
switch(date.DayOfWeek)   
{   
case System.DayOfWeek.Monday:   
case System.DayOfWeek.Tuessday:   
case System.DayOfWeek.Wednesday:   
case System.DayOfWeek.Thursday:   
case System.DayOfWeek.Friday:   
mm=mm+1;   
break;   
}   
}   
return mm;   
}   
//获得任意两日期之间的有效工作日(不包括周六日)   
DateTime date1=Convert.ToDateTime("2008-8-8");   
DateTime date2=Convert.ToDateTime("2008-10-1");   
int days=getDays(date1,date2);   
//调用如上即可获得   
private int getDays(System.DateTime date1,System.DateTime date2)   
{   
string m=Microsoft.VisualBasic.DateAndTime.DateDiff(EnumDateCompare.day,date1,date2).ToString("f0");   
int mm=0;   
for(int i=0;i<=Convert.ToInt32(m);i++)   
{   
System.DateTime date=Convert.ToDateTime(date1.AddDays(i));   
switch(date.DayOfWeek)   
{   
case System.DayOfWeek.Monday:   
case System.DayOfWeek.Tuesday:   
case System.DayOfWeek.Wednesday:   
case System.DayOfWeek.Thursday:   
case System.DayOfWeek.Friday:   
mm=mm+1;   
break;   
}   
}   
return mm;   
}   
//格式输出   
private void Page_Load(object sender,System.EventArgs e)   
{   
System.Globalization.DateTimeFormatInfo myDTFI=new System.Globalization.CultureInfo("en-US",false).DateTimeFormat;   
//中国为zh-cn   
DateTime myDT=System.DateTime.Now;   
Response.Write(myDT.ToString("f",myDTFI));   
//获得本周的周六和周日   
public static void ConvertDateToWeek(DateTime date,out DateTime firstdate,out DateTime lastdate)   
{   
DateTime first System.DateTime.Now;   
DateTime last=System.DateTime.Now;   
switch(date.DayOfWeek)   
{   
case System.DayOfWeek.Monday:   
first=date.AddDays(-1);   
last=date.AddDays(5);   
break;   
case System.DayOfWeek.Tuesday:   
first=date.AddDays(-2);   
last=date.AddDays(4);   
break;   
case System.DayOfWeek.Wednesday:   
first=date.AddDays(-3);   
last=date.AddDays(3);   
break;   
case System.DayOfWeek.Thursday:   
first=date.AddDays(-4);   
last=date.AddDays(2);   
break;   
case System.DayOfWeek.Friday:   
first=date.AddDays(-5);   
last=date.AddDays(1);   
break;   
case System.DayOfWeek.Saturday:   
first=dateAddDays(-6);   
last=date;   
break;   
case System.DayOfWeek.Sunday:   
first=date;   
last=date.AddDays(6);   
break;   
}   
firstdate=first;   
lastdate=last;   
}   
//调用   
DateTime firstdate=System.DateTime.Now;   
DateTime lastdate=System.Datetime.Now;   
ConvertDateToWeek(date,out firstdate,out lastdate);   
//获得当前日期是该年度的第几周   
DateTime dt=Convert.ToDateTime("2008-8-8");   
int weeks=dt.DayOfYear/7+1;  

 

posted on 2018-10-30 08:41  _ali  阅读(230)  评论(0编辑  收藏  举报

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