获取给定日期的正确的周数 [英] Get the correct week number of a given date

问题描述

我用Google搜索了很多，发现了很多解决方案，但他们都不给我了2012-12-31正确的周数。即使MSDN（<上一个例子href="http://msdn.microsoft.com/en-us/library/system.globalization.calendar.getweekofyear.aspx">link)失败。

2012-12-31就是星期一，所以它应该是第1周，但是每一个方法我试过给我53.下面是一些方法，我已经尝试过：

从MDSN库：

 的DateTimeFormatInfo DFI = DateTimeFormatInfo.CurrentInfo;
日历CAL = dfi.Calendar;

返回cal.GetWeekOfYear（日期，dfi.CalendarWeekRule，dfi.FirstDayOfWeek）;
 

解决方案2：

 返回新的GregorianCalendar（GregorianCalendarTypes.Localized）.GetWeekOfYear（日期，CalendarWeekRule.FirstFourDayWeek，DayOfWeek.Monday）;
 

解决方案3：

 的CultureInfo ciCurr = CultureInfo.CurrentCulture;
INT WEEKNUM = ciCurr.Calendar.GetWeekOfYear（dtPassed，CalendarWeekRule.FirstFourDayWeek，DayOfWeek.Monday）;
返回WEEKNUM;
 

更新

下面的方法实际上返回1时的日期是2012-12-31。换句话说，我的问题是，我的方法不符合ISO-8601标准。

  //这presumes这周开始的星期一。
//第1周是一年一个周四在它的第一个星期。
公共静态INT GetIso8601WeekOfYear（DateTime的时间）
{
    //严重作弊。如果周一，周二或周三，那么它会
    //是同一周＃作为任何周四，周五或周六是，
    //我们总是让那些权
    DAYOFWEEK天= CultureInfo.InvariantCulture.Calendar.GetDayOfWeek（时间）;
    如果（天＆GT; = DayOfWeek.Monday和放大器;和天＆LT; = DayOfWeek.Wednesday）
    {
        时间= time.AddDays（3）;
    }

    //返回我们调整星期
    返回CultureInfo.InvariantCulture.Calendar.GetWeekOfYear（时间，CalendarWeekRule.FirstFourDayWeek，DayOfWeek.Monday）;
}
 

解决方案

正如在此的 MSDN页面有ISO8601周和.Net周编号之间的细微差别。

您可以参考这篇文章在MSDN博客的一个更好的解释：<一href="http://blogs.msdn.com/b/shawnste/archive/2006/01/24/iso-8601-week-of-year-format-in-microsoft-net.aspx">ISO 8601周的年份格式，微软的.Net

简单地说，净让周以跨年分裂，而ISO标准没有。 在文章中也有一个简单的函数来得到正确的ISO 8601的周数为今年的最后一个星期。

更新下面的方法实际上返回1 2012-12-31 这是正确的ISO 8601（如德国）。

  //这presumes这周开始的星期一。
//第1周是一年一个周四在它的第一个星期。
公共静态INT GetIso8601WeekOfYear（DateTime的时间）
{
    //严重作弊。如果周一，周二或周三，那么它会
    //是同一周＃作为任何周四，周五或周六是，
    //我们总是让那些权
    DAYOFWEEK天= CultureInfo.InvariantCulture.Calendar.GetDayOfWeek（时间）;
    如果（天＆GT; = DayOfWeek.Monday和放大器;和天＆LT; = DayOfWeek.Wednesday）
    {
        时间= time.AddDays（3）;
    }

    //返回我们调整星期
    返回CultureInfo.InvariantCulture.Calendar.GetWeekOfYear（时间，CalendarWeekRule.FirstFourDayWeek，DayOfWeek.Monday）;
}
 

I have Googled a lot and found a lot of solutions, but none of them give me the correct week number for the 2012-12-31. Even the example on MSDN (link) fails.

2012-12-31 is Monday, therefore it should be Week 1, but every method I tried gives me 53. Here are some of the methods, that I have tried:

From the MDSN Library:

DateTimeFormatInfo dfi = DateTimeFormatInfo.CurrentInfo;
Calendar cal = dfi.Calendar;

return cal.GetWeekOfYear(date, dfi.CalendarWeekRule, dfi.FirstDayOfWeek);

Solution 2:

return new GregorianCalendar(GregorianCalendarTypes.Localized).GetWeekOfYear(date, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);

Solution 3:

CultureInfo ciCurr = CultureInfo.CurrentCulture;
int weekNum = ciCurr.Calendar.GetWeekOfYear(dtPassed, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
return weekNum;

Update

The following method actually returns 1 when date is 2012-12-31. In other words, my problem was that my methods were not following the ISO-8601 standard.

// This presumes that weeks start with Monday.
// Week 1 is the 1st week of the year with a Thursday in it.
public static int GetIso8601WeekOfYear(DateTime time)
{
    // Seriously cheat.  If its Monday, Tuesday or Wednesday, then it'll 
    // be the same week# as whatever Thursday, Friday or Saturday are,
    // and we always get those right
    DayOfWeek day = CultureInfo.InvariantCulture.Calendar.GetDayOfWeek(time);
    if (day >= DayOfWeek.Monday && day <= DayOfWeek.Wednesday)
    {
        time = time.AddDays(3);
    }

    // Return the week of our adjusted day
    return CultureInfo.InvariantCulture.Calendar.GetWeekOfYear(time, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
}

解决方案

As noted in this MSDN page there is a slight difference between ISO8601 week and .Net week numbering.

You can refer to this article in MSDN Blog for a better explanation: "ISO 8601 Week of Year format in Microsoft .Net"

Simply put, .Net allow weeks to be split across years while the ISO standard does not. In the article there is also a simple function to get the correct ISO 8601 week number for the last week of the year.

Update The following method actually returns 1 for 2012-12-31 which is correct in ISO 8601 (e.g. Germany).

// This presumes that weeks start with Monday.
// Week 1 is the 1st week of the year with a Thursday in it.
public static int GetIso8601WeekOfYear(DateTime time)
{
    // Seriously cheat.  If its Monday, Tuesday or Wednesday, then it'll 
    // be the same week# as whatever Thursday, Friday or Saturday are,
    // and we always get those right
    DayOfWeek day = CultureInfo.InvariantCulture.Calendar.GetDayOfWeek(time);
    if (day >= DayOfWeek.Monday && day <= DayOfWeek.Wednesday)
    {
        time = time.AddDays(3);
    }

    // Return the week of our adjusted day
    return CultureInfo.InvariantCulture.Calendar.GetWeekOfYear(time, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
} 

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