//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，進而得知本周的第一天就是幾天前的那一天，要注意的是這裡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該懂了
//由于DayOfWeek傳回的是數字的星期幾，我們要把它轉換成漢字友善我們閱讀，有些人可能會用switch來一個一個地對照，其實不用那麼麻煩的
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,很多人都會說本月的第一天嘛肯定是1号，最後一天就是下個月一号再減一天。當然這是對的
//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();//最後一天
//巧用C#裡ToString的字元格式化更簡便
DateTime.Now.ToString("yyyy-MM-01");
DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).AddDays(-1).ToShortDateString();
//上個月，減去一個月份
DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(-1).ToShortDateString();
DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
//下個月，加去一個月份
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天後
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的字元格式化我們也很容易地算出本年度的第一天和最後一天
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，很多人都會覺得這裡難點，需要寫個長長的過程來判斷。其實不用的，我們都知道一年四個季度，一個季度三個月
//首先我們先把日期推到本季度第一個月，然後這個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，本季度的最後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
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();
//如何獲得當月有多少天
int m=System.DateTime.DaysInMonth(System.DateTime.Now.Year,System.DateTime.Now.Month);
//擷取某月的實際工作日(即不包括周六日)
//調用
//int days =getDays(System.DateTime.Now));
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.Thursday:
case System.DayOfWeek.Tuesday:
case System.DayOfWeek.Wednesday:
case System.DayOfWeek.Friday:
mm=mm+1;
break;
}
}
return mm;
}
獲得任意兩日期之間的有效工作日(不包括周六日) 獲得任意兩日期之間的有效工作日(不包括周六日)#region 獲得任意兩日期之間的有效工作日(不包括周六日)
//調用
//DateTime date1=Convert.ToDateTime("2005-10-20");
//DateTime date2=Convert.ToDateTime("2005-11-01");
//int days =getDays(date1,date2);
private int getDays(System.DateTime date1,System.DateTime date2)
{
string m=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.Thursday:
case System.DayOfWeek.Tuesday:
case System.DayOfWeek.Wednesday:
case System.DayOfWeek.Friday:
mm=mm+1;
break;
}
}
return mm;
}
#endregion
格式輸出
格式輸出#region 格式輸出 private void Page_Load(object sender, System.EventArgs e) { System.Globalization.DateTimeFormatInfo myDTFI = new System.Globalization.CultureInfo( "en-US", false ).DateTimeFormat; //中國用zh-cn DateTime myDT =System.DateTime.Now; Response.Write(myDT.ToString("f",myDTFI)); /**//**//**//* This code produces the following output. FORMAT en-US EXAMPLE CHAR VALUE OF ASSOCIATED PROPERTY, IF ANY d 1/3/2002 M/d/yyyy (ShortDatePattern) D Thursday, January 03, 2002 dddd, MMMM dd, yyyy (LongDatePattern) f Thursday, January 03, 2002 12:00 AM F Thursday, January 03, 2002 12:00:00 AM dddd, MMMM dd, yyyy h:mm:ss tt (FullDateTimePattern) g 1/3/2002 12:00 AM G 1/3/2002 12:00:00 AM m January 03 MMMM dd (MonthDayPattern) M January 03 MMMM dd (MonthDayPattern) r Thu, 03 Jan 2002 00:00:00 GMT ddd, dd MMM yyyy HH':'mm':'ss 'GMT' (RFC1123Pattern) R Thu, 03 Jan 2002 00:00:00 GMT ddd, dd MMM yyyy HH':'mm':'ss 'GMT' (RFC1123Pattern) s 2002-01-03T00:00:00 yyyy'-'MM'-'dd'T'HH':'mm':'ss (SortableDateTimePattern) t 12:00 AM h:mm tt (ShortTimePattern) T 12:00:00 AM h:mm:ss tt (LongTimePattern) u 2002-01-03 00:00:00Z yyyy'-'MM'-'dd HH':'mm':'ss'Z' (UniversalSortableDateTimePattern) U Thursday, January 03, 2002 8:00:00 AM y January, 2002 MMMM, yyyy (YearMonthPattern) Y January, 2002 MMMM, yyyy (YearMonthPattern) */ } #endregion 獲得本周的周六和周日
ConvertDateToWeek#region ConvertDateToWeek 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=date.AddDays(-6); last=date; break; case System.DayOfWeek.Sunday: first=date; last=date.AddDays(6); break; } firstdate=first; lastdate=last; } #endregion //調用 DateTime firstdate=System.DateTime.Now; DateTime lastdate=System.DateTime.Now; ConvertDateToWeek(date,out firstdate,out lastdate); 獲得目前日期是該年度的第幾周 DateTime dt = Convert.ToDateTime("2006-05-01"); int weeks = dt.DayOfYear / 7 + 1;