blocks|key|488308|text|谢谢你所有的答案。我还进行了更多的搜索，最终创建了两个C#方法来实现我想要的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|488309|首先，在http://blogs.msdn.com/b/shawnste/archive/2006/01/24/iso-8601-week-of-year-format-in-microsoft-net.aspx的一条评论中找到了一个简洁的评论：|offset|length|488310|Jon+Senchyna还指出：|488311|+++++public+static+int+WeekNumber(this+DateTime+date)
++++{
++++++++Calendar+cal+=+CultureInfo.InvariantCulture.Calendar;
++++++++DayOfWeek+day+=+cal.GetDayOfWeek(date);
++++++++date+=+date.AddDays(4+-+((int)day+==+0+?+7+:+(int)day));
++++++++return+cal.GetWeekOfYear(date,+CalendarWeekRule.FirstFourDayWeek,+DayOfWeek.Monday);
++++}|code-block|syntax|javascript|488312|还有一位是：http://www.tondering.dk/claus/cal/week.php#calcweekno|488313|++++public+static+int+WeekNumber2(this+DateTime+date)
++++{
++++++++int+a;
++++++++int+b;
++++++++int+c;
++++++++int+s;
++++++++int+e;
++++++++int+f;

++++++++if+(date.Month+<=+2)
++++++++{
++++++++++++a+=+date.Year+-+1;
++++++++++++b+=+a+/+4+-+a+/+100+%2B+a+/+400;
++++++++++++c+=+(a+-+1)+/+4+-+(a+-+1)+/+100+%2B+(a+-+1)+/+400;
++++++++++++s+=+b+-+c;
++++++++++++e+=+0;
++++++++++++f+=+date.Day+-+1+%2B+31+*+(date.Month+-+1);
++++++++}
++++++++else
++++++++{
++++++++++++a+=+date.Year;
++++++++++++b+=+a+/+4+-+a+/+100+%2B+a+/+400;
++++++++++++c+=+(a+-+1)+/+4+-+(a+-+1)+/+100+%2B+(a+-+1)+/+400;
++++++++++++s+=+b+-+c;
++++++++++++e+=+s+%2B+1;
++++++++++++f+=+date.Day+%2B+((153+*+(date.Month+-+3)+%2B+2)+/+5)+%2B+58+%2B+s;
++++++++}

++++++++int+g+=+(a+%2B+b)+%25+7;
++++++++int+d+=+(f+%2B+g+-+e)+%25+7;
++++++++int+n+=+f+%2B+3+-+d;

++++++++if+(n+<+0)
++++++++++++return+53+-+((g+-+s)+/+5);
++++++++if+(n+>+(364+%2B+s))
++++++++++++return+1;
++++++++return+n+/+7+%2B+1;
++++}|488314|都给了我想要的。|488315|我还写了一个小的单元测试，证明它们在日历的前3000年返回相同的周数字。|488316|++++[TestMethod]
++++public+void+WeekNumbers_CorrectFor_3000Years()
++++{
++++++++var+weekNumbersMethod1+=+WeekNumbers3000Years(DateManipulation.WeekNumber).ToList();
++++++++var+weekNumbersMethod2+=+WeekNumbers3000Years(DateManipulation.WeekNumber2).ToList();
++++++++CollectionAssert.AreEqual(weekNumbersMethod1,+weekNumbersMethod2);
++++}

++++private+IEnumerable<int>+WeekNumbers3000Years(Func<DateTime,+int>+weekNumberCalculator)
++++{
++++++++var+startDate+=+new+DateTime(1,1,1);
++++++++var+endDate+=+new+DateTime(3000,+12,+31);
++++++++for(DateTime+date+=+startDate;+date+<+endDate;+date+=+date.AddDays(1))
++++++++++++yield+return+weekNumberCalculator(date);
++++}|488317|entityMap|0|LINK|mutability|MUTABLE|url|http://blogs.msdn.com/b/shawnste/archive/2006/01/24/iso-8601-week-of-year-format-in-microsoft-net.aspx|1|http://www.tondering.dk/claus/cal/week.php#calcweekno^0|0|4|2U|0|0|0|0|6|1H|1|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|17|8|@]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|F|3|G|5|6|7|1B|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|1C|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1D|8|@]|9|@$D|1E|E|1F|1|1G]]|A|$]]|$1|O|3|P|5|J|7|1H|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1I|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1J|8|@]|9|@]|A|$]]|$1|U|3|V|5|J|7|1K|8|@]|9|@]|A|$K|L]]|$1|W|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]|14|$5|Z|10|11|A|$12|15]]]]

Thanks for all the answers. I also searched some more and finally created two C# methods to achieve what I wanted:

First a concise one found in one of the comments at:
<a href="http://blogs.msdn.com/b/shawnste/archive/2006/01/24/iso-8601-week-of-year-format-in-microsoft-net.aspx" rel="nofollow">http://blogs.msdn.com/b/shawnste/archive/2006/01/24/iso-8601-week-of-year-format-in-microsoft-net.aspx</a>

Which Jon Senchyna also pointed to:

<pre><code> public static int WeekNumber(this DateTime date)
 {
 Calendar cal = CultureInfo.InvariantCulture.Calendar;
 DayOfWeek day = cal.GetDayOfWeek(date);
 date = date.AddDays(4 - ((int)day == 0 ? 7 : (int)day));
 return cal.GetWeekOfYear(date, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
 }
</code></pre>

And also one at:
<a href="http://www.tondering.dk/claus/cal/week.php#calcweekno" rel="nofollow">http://www.tondering.dk/claus/cal/week.php#calcweekno</a>

<pre><code> public static int WeekNumber2(this DateTime date)
 {
 int a;
 int b;
 int c;
 int s;
 int e;
 int f;

 if (date.Month &lt;= 2)
 {
 a = date.Year - 1;
 b = a / 4 - a / 100 + a / 400;
 c = (a - 1) / 4 - (a - 1) / 100 + (a - 1) / 400;
 s = b - c;
 e = 0;
 f = date.Day - 1 + 31 * (date.Month - 1);
 }
 else
 {
 a = date.Year;
 b = a / 4 - a / 100 + a / 400;
 c = (a - 1) / 4 - (a - 1) / 100 + (a - 1) / 400;
 s = b - c;
 e = s + 1;
 f = date.Day + ((153 * (date.Month - 3) + 2) / 5) + 58 + s;
 }

 int g = (a + b) % 7;
 int d = (f + g - e) % 7;
 int n = f + 3 - d;

 if (n &lt; 0)
 return 53 - ((g - s) / 5);
 if (n &gt; (364 + s))
 return 1;
 return n / 7 + 1;
 }
</code></pre>

Both gave me what I wanted.

I also wrote a small unittest that proves that they return the same weeknumbers for the first 3000 years of the calendar.

<pre><code> [TestMethod]
 public void WeekNumbers_CorrectFor_3000Years()
 {
 var weekNumbersMethod1 = WeekNumbers3000Years(DateManipulation.WeekNumber).ToList();
 var weekNumbersMethod2 = WeekNumbers3000Years(DateManipulation.WeekNumber2).ToList();
 CollectionAssert.AreEqual(weekNumbersMethod1, weekNumbersMethod2);
 }

 private IEnumerable&lt;int&gt; WeekNumbers3000Years(Func&lt;DateTime, int&gt; weekNumberCalculator)
 {
 var startDate = new DateTime(1,1,1);
 var endDate = new DateTime(3000, 12, 31);
 for(DateTime date = startDate; date &lt; endDate; date = date.AddDays(1))
 yield return weekNumberCalculator(date);
 }
</code></pre>

blocks|key|271272|text|您可以使用以下代码来计算给定日期的周数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|271273|++++public+static+int+GetWeekNumber(DateTime+date)
++++{
++++++++var+firstDayOfYear+=+new+DateTime(date.Year,+1,+1);
++++++++var+lastDayOfYear+=+new+DateTime(date.Year,+12,+31);
++++++++var+lastDayOfPreviousYear+=+new+DateTime(date.Year+-+1,+12,+31);

++++++++var+weekDayOfFirstDayOfYear+=+(int)firstDayOfYear.DayOfWeek+%2B+1;
++++++++var+weekDayOfLastDayOfYear+=+(int)lastDayOfYear.DayOfWeek+%2B+1;
++++++++var+days+=+(date+-+firstDayOfYear).Days;

++++++++if+(days+<=+7+-+weekDayOfFirstDayOfYear)++//+My+day+fall+in+1'st+week+of+the+year
++++++++{
++++++++++++if+(weekDayOfFirstDayOfYear+>+5)
++++++++++++++++return+GetWeekNumber(lastDayOfPreviousYear);
++++++++++++return+1;
++++++++}
++++++++else+//+My+day+fall+not+on+1'st+week+of+the+year
++++++++{
++++++++++++//+Number+of+weeks+that+pass+from+1'st+Sunday+of+2'nd+week+of+the+year
++++++++++++var+weekNo+=+((days+-+(8+-+weekDayOfFirstDayOfYear))+/+7)+%2B+1;

++++++++++++if+(weekDayOfFirstDayOfYear+<+6)++//+if+Year+start+at+Sun...Thursday+the+first+week+is+added.
++++++++++++++++weekNo%2B%2B;

++++++++++++//+Check+if+Last+week+of+the+year+belong+to+next+year
++++++++++++if+(weekDayOfLastDayOfYear+<+5)+//+if+the+year+end+in+Sunday+to+Wednesday+then+it+might+belong+to+the+1'st+week+of+the+next+year
++++++++++++{
++++++++++++++++if+((lastDayOfYear+-+date).Days+<+weekDayOfLastDayOfYear)
++++++++++++++++{
++++++++++++++++++++return+1;
++++++++++++++++}
++++++++++++}

++++++++++++return+weekNo;
++++++++}
++++}|code-block|syntax|javascript|271274|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can use the following code in order to calculate the week number for a given date:

<pre><code> public static int GetWeekNumber(DateTime date)
 {
 var firstDayOfYear = new DateTime(date.Year, 1, 1);
 var lastDayOfYear = new DateTime(date.Year, 12, 31);
 var lastDayOfPreviousYear = new DateTime(date.Year - 1, 12, 31);

 var weekDayOfFirstDayOfYear = (int)firstDayOfYear.DayOfWeek + 1;
 var weekDayOfLastDayOfYear = (int)lastDayOfYear.DayOfWeek + 1;
 var days = (date - firstDayOfYear).Days;

 if (days &lt;= 7 - weekDayOfFirstDayOfYear) // My day fall in 1'st week of the year
 {
 if (weekDayOfFirstDayOfYear &gt; 5)
 return GetWeekNumber(lastDayOfPreviousYear);
 return 1;
 }
 else // My day fall not on 1'st week of the year
 {
 // Number of weeks that pass from 1'st Sunday of 2'nd week of the year
 var weekNo = ((days - (8 - weekDayOfFirstDayOfYear)) / 7) + 1;

 if (weekDayOfFirstDayOfYear &lt; 6) // if Year start at Sun...Thursday the first week is added.
 weekNo++;

 // Check if Last week of the year belong to next year
 if (weekDayOfLastDayOfYear &lt; 5) // if the year end in Sunday to Wednesday then it might belong to the 1'st week of the next year
 {
 if ((lastDayOfYear - date).Days &lt; weekDayOfLastDayOfYear)
 {
 return 1;
 }
 }

 return weekNo;
 }
 }
</code></pre>

I have a rather weird problem. I live in denmark and here the first week (Week 1) of 2013 starts the 31th of december 2012 and lasts for 7 days - as weeks normally do :)

According to .NET however the 30th of december is Week 52, the 31th is Week 53 and the 1st of January is Week 1.

Week 53 lasts for only one day, and Week 1 for 6 days. Clearly this must be wrong (a week consisting of less than 7 days) and certainly is wrong in danish context. Where the 31th of december is Week 1, NOT Week 53.

The following code illustrates the problem (CurrentCulture is "da-DK")

<pre><code> static void Main(string[] args)
 {
 //Here I get Monday
 DayOfWeek firstDayOfWeek = DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek; 
 //Here I get FirstFourDayWeek
 CalendarWeekRule weekRule = DateTimeFormatInfo.CurrentInfo.CalendarWeekRule; 

 DateTime date = new DateTime(2012,12,30);

 for (int i = 0; i &lt;= 10; i++)
 {
 DateTime currentDate = date.AddDays(i);
 Console.WriteLine("Date: {0} WeekNumber: {1}",
 currentDate.ToShortDateString(),
 CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(currentDate, weekRule, firstDayOfWeek));
 }
 Console.ReadLine();
 }
</code></pre>

Have I done something wrong or is this a bug in .NET ? If the latter - do you have suggestions for calculating weeknumbers correctly ?

Bug in WeekNumber calculation .NET?

单元测试

我有一个相当奇怪的问题。我住在丹麦，2013年的第一周(第一周)从2012年12月31日开始，持续7天--就像往常一样:)根据.NET的说法，12月30日是52周，31号是53周，1月1日是1周。第53周仅持续一天，第1周持续6天。显然，这肯定是错误的(一周由不到7天组成)，在丹麦上下文中肯定是错误的。其中12月31日...

问WeekNumber calculation .NET中的错误？
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