C# 根据年、月、周、星期获得日期等
2012-02-29 11:01 CuiWenKe 阅读(3566) 评论(1) 编辑 收藏 举报/// 取得某月的第一天
- /// </summary>
- /// <param name="datetime">要取得月份第一天的时间</param>
- /// <returns></returns>
- private DateTime FirstDayOfMonth(DateTime datetime)
- {
- return datetime.AddDays(1 - datetime.Day);
- }
- /**//// <summary>
- /// 取得某月的最后一天
- /// </summary>
- /// <param name="datetime">要取得月份最后一天的时间</param>
- /// <returns></returns>
- private DateTime LastDayOfMonth(DateTime datetime)
- return datetime.AddDays(1 - datetime.Day).AddMonths(1).AddDays(-1);
- }
- /**//// <summary>
- /// 取得上个月第一天
- /// </summary>
- /// <param name="datetime">要取得上个月第一天的当前时间</param>
- /// <returns></returns>
- private DateTime FirstDayOfPreviousMonth(DateTime datetime)
- {
- return datetime.AddDays(1 - datetime.Day).AddMonths(-1);
- }
- /**//// <summary>
- /// 取得上个月的最后一天
- /// </summary>
- /// <param name="datetime">要取得上个月最后一天的当前时间</param>
- /// <returns></returns>
- private DateTime LastDayOfPrdviousMonth(DateTime datetime)
- {
- return datetime.AddDays(1 - datetime.Day).AddDays(-1);
- }
C# DateTime 日期加1天 减一天 加一月 减一月 等方法
- //今天
- DateTime.Now.Date.ToShortDateString();
- //昨天,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(要知道本周的第一天就得先知道今天是星期几,从而得知本周的第一天就是几天前的那一天,要注意的是这里的每一周是从周日始至周六止
- 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" };
- Day[Convert.ToInt16(DateTime.Now.DayOfWeek)];
- //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.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)).ToString("yyyy-MM-01");
- //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)).ToString("yyyy-MM-01");
- DateTime.Parse(DateTime.Now.AddMonths(0 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
-
c# 根据日期获取星期方法
protected void Page_Load(object sender, EventArgs e)
{
int m = System.DateTime.Today.Month;
int y = System.DateTime.Today.Year;
int d = System.DateTime.Today.Day;
int weeks = getWeekDay(y, m, d);
switch (weeks)
{
case 1:
this.TextBox1.Text = "星期一";
break;
case 2:
this.TextBox1.Text = "星期二";
break;
case 3:
this.TextBox1.Text = "星期三";
break;
case 4:
this.TextBox1.Text = "星期四";
break;
case 5:
this.TextBox1.Text = "星期五";
break;
case 6:
this.TextBox1.Text = "星期六";
break;
case 7:
this.TextBox1.Text = "星期日";
break;
}
}/// <summary>根据日期,获得星期几</summary>
/// <param name="y">年</param>
/// <param name="m">月</param>
/// <param name="d">日</param>
/// <returns>星期几,1代表星期一;7代表星期日</returns>
public static int getWeekDay(int y, int m, int d)
{
if (m == 1) m = 13;
if (m == 2) m = 14;
int week = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7 + 1;
return week;
} -
C# 根据年、月、周、星期获得日期等
/// <summary>
/// 取指定日期是一年中的第几周
/// </summary>
/// <param name="dtime">给定的日期</param>
/// <returns>数字 一年中的第几周</returns>
public
static
int
WeekOfYear(DateTime dtime)
{
try
{
//确定此时间在一年中的位置
int
dayOfYear = dtime.DayOfYear;
//当年第一天
DateTime tempDate =
new
DateTime(dtime.Year, 1, 1);
//确定当年第一天
int
tempDayOfWeek = (
int
)tempDate.DayOfWeek;
tempDayOfWeek = tempDayOfWeek == 0 ? 7 : tempDayOfWeek;
////确定星期几
int
index = (
int
)dtime.DayOfWeek;
index = index == 0 ? 7 : index;
//当前周的范围
DateTime retStartDay = dtime.AddDays(-(index - 1));
DateTime retEndDay = dtime.AddDays(6 - index);
//确定当前是第几周
int
weekIndex = (
int
)Math.Ceiling(((
double
)dayOfYear + tempDayOfWeek - 1) / 7);
if
(retStartDay.Year < retEndDay.Year)
{
weekIndex = 1;
}
return
weekIndex;
}
catch
(Exception ex)
{
throw
new
Exception(ex.Message);
}
}
/// <summary>
/// 求某年有多少周
/// </summary>
/// <param name="dtime"></param>
/// <returns></returns>
public
static
int
GetWeekOfYear(DateTime dtime)
{
int
countDay = DateTime.Parse(dtime.Year +
"-12-31"
).DayOfYear;
int
countWeek = countDay / 7;
return
countWeek;
}
//根据年月日获得星期几
public
static
string
CaculateWeekDay(
int
month,
int
day)
{
string
weekstr =
string
.Empty;
int
year = DateTime.Now.Year;
//把一月和二月看成是上一年的十三月和十四月
if
(month == 1) { month = 13; year--; }
if
(month == 2) { month = 14; year--; }
int
week = (day + 2 * month + 3 * (month + 1) / 5 + year + year / 4 - year / 100 + year / 400) % 7;
switch
(week)
{
case
0: weekstr =
"1"
;
break
;
case
1: weekstr =
"2"
;
break
;
case
2: weekstr =
"3"
;
break
;
case
3: weekstr =
"4"
;
break
;
case
4: weekstr =
"5"
;
break
;
case
5: weekstr =
"6"
;
break
;
case
6: weekstr =
"7"
;
break
;
}
return
weekstr;
}
/// <summary>
/// 根据2个时间段获得相应的周数
/// </summary>
/// <param name="beginDate"></param>
/// <param name="endDate"></param>
/// <returns></returns>
public
static
int
WeekOfDate(DateTime beginDate, DateTime endDate)
{
TimeSpan ts1 =
new
TimeSpan(beginDate.Ticks);
TimeSpan ts2 =
new
TimeSpan(endDate.Ticks);
TimeSpan ts = ts2.Subtract(ts1).Duration();
int
weeks = ts.Days / 7;
//确定此时间在一年中的位置
int
dayOfYear = beginDate.DayOfYear;
//当年第一天
DateTime tempDate =
new
DateTime(beginDate.Year, beginDate.Month, beginDate.Day);
//最后一天
DateTime tempendDate =
new
DateTime(endDate.Year, endDate.Month, endDate.Day);
int
tempDayOfWeek = (
int
)tempDate.DayOfWeek;
tempDayOfWeek = tempDayOfWeek == 0 ? 7 : tempDayOfWeek;
////确定星期几
int
startindex = (
int
)beginDate.DayOfWeek;
startindex = startindex == 0 ? 7 : startindex;
//当前周的范围
DateTime retStartDay = beginDate.AddDays(-(startindex - 1));
DateTime retEndDay = beginDate.AddDays(7 - startindex);
//确定当前是第几周
int
weekIndex = (
int
)Math.Ceiling(((
double
)dayOfYear + tempDayOfWeek - 1) / 7);
return
weeks;
}
/// <summary>
/// 根据起始时间,获取第几周
/// </summary>
/// <param name="dtime">当前时间</param>
/// <returns></returns>
public
static
int
WeekOfTermDate(DateTime dtime)
{
string
datetime =
"2011-3-1"
;
TimeSpan ts1 =
new
TimeSpan(dtime.Ticks);
TimeSpan ts2 =
new
TimeSpan(Convert.ToDateTime(datetime).Ticks);
TimeSpan ts = ts2.Subtract(ts1).Duration();
//确定此时间在一年中的位置
int
dayOfYear = ts.Days;
//当年第一天
DateTime tempDate =
new
DateTime(Convert.ToDateTime(datetime).Year, Convert.ToDateTime(datetime).Month, Convert.ToDateTime(datetime).Day);
int
tempDayOfWeek = (
int
)tempDate.DayOfWeek;
tempDayOfWeek = tempDayOfWeek == 0 ? 7 : tempDayOfWeek;
////确定星期几
int
index = (
int
)dtime.DayOfWeek;
index = index == 0 ? 7 : index;
//当前周的范围
DateTime retStartDay = dtime.AddDays(-(index - 1));
DateTime retEndDay = dtime.AddDays(7 - index);
//确定当前是第几周
int
weekIndex = (
int
)Math.Ceiling(((
double
)dayOfYear + tempDayOfWeek) / 7);
return
weekIndex;
}
/// <summary>
/// 根据周,星期获得具体年月日
/// </summary>
/// <param name="week">第几周</param>
/// <param name="day">星期几</param>
/// <returns></returns>
public
static
DateTime DateTimeByWeekAndDay(
int
week,
int
day)
{
DateTime someTime = Convert.ToDateTime(
"2011-3-1"
);
int
i = someTime.DayOfWeek - DayOfWeek.Monday;
if
(i == -1) i = 6;
// i值 > = 0 ,因为枚举原因,Sunday排在最前,此时Sunday-Monday=-1,必须+7=6。
TimeSpan ts =
new
TimeSpan(i, 0, 0, 0);
//获取第N周的星期一
someTime = someTime.Subtract(ts).AddDays((week - 1) * 7);
//获得星期几
someTime = someTime.AddDays(day - 1);
return
someTime;
}
private static int GetWeekOfYear()
{
//一.找到第一周的最后一天(先获取1月1日是星期几,从而得知第一周周末是几)
int firstWeekend=7-Convert.ToInt32(DateTime.Parse(DateTime.Today.Year + "-1-1").DayOfWeek);
//二.获取今天是一年当中的第几天
int currentDay = DateTime.Today.DayOfYear;//三.(今天 减去 第一周周末)/7 等于 距第一周有多少周 再加上第一周的1 就是今天是今年的第几周了
// 刚好考虑了惟一的特殊情况就是,今天刚好在第一周内,那么距第一周就是0 再加上第一周的1 最后还是1
return Convert.ToInt32(Math.Ceiling((currentDay - firstWeekend) / 7.0)) + 1;
}