获取给定日期的正确星期数

  • Z时代
  • 2024-01-10
  • 分类：问答

我在Google上搜索了很多，找到了很多解决方案，但是没有一个给我正确的2012-12-31周数。甚至MSDN（link）上的示例也失败了。

2012-12-31是星期一，因此应该是第1周，但是我尝试的每种方法都给了我53。这是我尝试过的一些方法：

从MDSN库：

DateTimeFormatInfo dfi = DateTimeFormatInfo.CurrentInfo;
Calendar cal = dfi.Calendar;
return cal.GetWeekOfYear(date, dfi.CalendarWeekRule, dfi.FirstDayOfWeek);

解决方案2：

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

解决方案3：

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

当日期为2012-12-31时，以下方法实际上返回1。换句话说，我的问题是我的方法未遵循ISO-8601标准。

// 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);
}

回答：

如该MSDN页面中所述，ISO8601周和.Net周编号之间存在细微差异。

您可以在MSDN博客中参考本文以获得更好的解释：“ Microsoft .Net中的ISO

8601年度格式 ”

简而言之，.Net允许将数年的时间分成数年，而ISO标准则不允许。在文章中，还有一个简单的函数可以为一年的最后一周获取正确的ISO 8601周编号。

以下方法实际上返回1，2012-12-31在ISO 8601中该值是正确的（例如德国）。

// 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);
}

以上是 获取给定日期的正确星期数 的全部内容， 来源链接： utcz.com/qa/398378.html

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