blocks|key|1411155|text|如果星期天是一周的第一天，您可以简单地这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1411156|Dim+today+As+Date+=+Date.Today
Dim+dayDiff+As+Integer+=+today.DayOfWeek+-+DayOfWeek.Monday
Dim+monday+As+Date+=+today.AddDays(-dayDiff)|code-block|syntax|javascript|1411157|如果星期一是一周的第一天：|1411158|Dim+today+As+Date+=+Date.Today
Dim+dayIndex+As+Integer+=+today.DayOfWeek
If+dayIndex+<+DayOfWeek.Monday+Then
++++dayIndex+%2B=+7+'Monday+is+first+day+of+week,+no+day+of+week+should+have+a+smaller+index
End+If
Dim+dayDiff+As+Integer+=+dayIndex+-+DayOfWeek.Monday
Dim+monday+As+Date+=+today.AddDays(-dayDiff)|1411159|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

If Sunday is the first day of week, you can simply do this:

<pre><code>Dim today As Date = Date.Today
Dim dayDiff As Integer = today.DayOfWeek - DayOfWeek.Monday
Dim monday As Date = today.AddDays(-dayDiff)
</code></pre>

If Monday is the first day of week:

<pre><code>Dim today As Date = Date.Today
Dim dayIndex As Integer = today.DayOfWeek
If dayIndex &lt; DayOfWeek.Monday Then
 dayIndex += 7 'Monday is first day of week, no day of week should have a smaller index
End If
Dim dayDiff As Integer = dayIndex - DayOfWeek.Monday
Dim monday As Date = today.AddDays(-dayDiff)
</code></pre>

blocks|key|1411084|text|DateTime.DayOfWeek是一个枚举，它指示给定日期是哪一天。由于星期一是1，您可以使用以下代码查找当前周的星期一：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1411085|Dim+monday+As+DateTime+=+Today.AddDays((Today.DayOfWeek+-+DayOfWeek.Monday)+*+-1)|code-block|syntax|javascript|1411086|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|$]]

DateTime.DayOfWeek is an enum that indicates what day a given date is. As Monday is 1, you can find the Monday of the current week using the following code:

<pre><code>Dim monday As DateTime = Today.AddDays((Today.DayOfWeek - DayOfWeek.Monday) * -1)
</code></pre>

blocks|key|1195802|text|=Format(DateAdd("d",+(-1+*+WeekDay(Date.Today())+%2B+2),+Date.Today()),+"dd/MM/yyyy")|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1195803|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>=Format(DateAdd("d", (-1 * WeekDay(Date.Today()) + 2), Date.Today()), "dd/MM/yyyy")
</code></pre>

blocks|key|1195899|text|一个简单的方法应该会得到你想要的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1195900|++++private+static+DateTime+GetMondayForWeek(DateTime+inputDate)
++++{
++++++++int+daysFromMonday+=+inputDate.DayOfWeek+-+DayOfWeek.Monday;
++++++++return+inputDate.AddDays(-daysFromMonday);
++++}|code-block|syntax|javascript|1195901|你也可以把它延长到你想要的任何一天：|1195902|++++private+static+DateTime+GetDayForWeek(DateTime+inputDate,+DayOfWeek+inputDay)
++++{
++++++++int+daysAway+=+inputDate.DayOfWeek+-+inputDay;
++++++++return+inputDate.AddDays(-daysAway);
++++}|1195903|要调用第一个示例，只需使用如下内容：|1195904|DateTime+mondayDate+=+GetMondayForWeek(new+DateTime(2009,+11,+15));
Console.WriteLine(mondayDate);|1195905|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

A simple method should get you what you want:

<pre><code> private static DateTime GetMondayForWeek(DateTime inputDate)
 {
 int daysFromMonday = inputDate.DayOfWeek - DayOfWeek.Monday;
 return inputDate.AddDays(-daysFromMonday);
 }
</code></pre>

You could also extend it for any day that you want as well:

<pre><code> private static DateTime GetDayForWeek(DateTime inputDate, DayOfWeek inputDay)
 {
 int daysAway = inputDate.DayOfWeek - inputDay;
 return inputDate.AddDays(-daysAway);
 }
</code></pre>

To call the first example just use something like:

<pre><code>DateTime mondayDate = GetMondayForWeek(new DateTime(2009, 11, 15));
Console.WriteLine(mondayDate);
</code></pre>

blocks|key|1196157|text|如果星期一是第一天，另一种方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1196158|+Dim+today+As+Date+=+Date.Today
++++++++++++++++Dim+dayDiff+As+Integer+=+today.DayOfWeek+-+DayOfWeek.Monday
++++++++++++++++Dim+monday+As+Date+=+today.AddDays(-dayDiff)

++++++++++++++++dayDiff+=+DayOfWeek.Saturday+-+today.DayOfWeek+%2B+1
++++++++++++++++Dim+sunday+As+Date+=+today.AddDays(dayDiff)|code-block|syntax|javascript|1196159|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|$]]

Another approach if Monday is the first day, is this:

<pre><code> Dim today As Date = Date.Today
 Dim dayDiff As Integer = today.DayOfWeek - DayOfWeek.Monday
 Dim monday As Date = today.AddDays(-dayDiff)

 dayDiff = DayOfWeek.Saturday - today.DayOfWeek + 1
 Dim sunday As Date = today.AddDays(dayDiff)
</code></pre>

blocks|key|1411250|text|有一个星期的方法，你可以使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1411251|Dim+instance+As+DateTime
Dim+value+As+DayOfWeek

value+=+instance.DayOfWeek|code-block|syntax|javascript|1411252|请参阅：http://msdn.microsoft.com/en-us/library/system.datetime.dayofweek.aspx|offset|length|1411253|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.datetime.dayofweek.aspx^0|0|0|4|1Y|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

There is a day of week method that you can use

<pre><code>Dim instance As DateTime
Dim value As DayOfWeek

value = instance.DayOfWeek
</code></pre>

see: <a href="http://msdn.microsoft.com/en-us/library/system.datetime.dayofweek.aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/library/system.datetime.dayofweek.aspx</a>

blocks|key|1196015|text|我只是在我正在做的一个项目中这样做的--我保证，它是正确的。这是一个返回给定日期后的第n个星期一的方法。如果给定的日期是星期一，则返回下一个星期一。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1196016|Public+Function+GetSubsequentMonday(ByVal+startDate+As+DateTime,+ByVal+subsequentWeeks+As+Integer)+As+DateTime
++++Dim+dayOfWeek+As+Integer+=+CInt(startDate.DayOfWeek)
++++Dim+daysUntilMonday+As+Integer+=+(Math.Sign(dayOfWeek)+*+(7+-+dayOfWeek))+%2B+1
++++'number+of+days+until+the+next+Monday
++++Return+startDate.AddDays(CDbl((daysUntilMonday+%2B+(7+*+(subsequentWeeks+-+1)))))
End+Function|code-block|syntax|javascript|1196017|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|$]]

I just did this in a project I'm working on --I promise, it's correct. This is a method that returns the nth monday after the given date. If the given date is a monday, it returns the next monday.

<pre><code>Public Function GetSubsequentMonday(ByVal startDate As DateTime, ByVal subsequentWeeks As Integer) As DateTime
 Dim dayOfWeek As Integer = CInt(startDate.DayOfWeek)
 Dim daysUntilMonday As Integer = (Math.Sign(dayOfWeek) * (7 - dayOfWeek)) + 1
 'number of days until the next Monday
 Return startDate.AddDays(CDbl((daysUntilMonday + (7 * (subsequentWeeks - 1)))))
End Function
</code></pre>

blocks|key|1411366|text|在我对Meta-Knight的回答的评论之后，这里是一个简短的函数，它对我在评论中提到的更正进行了修正：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1411367|Public+Function+GetFirstOfLastWeek()+As+DateTime
Dim+today+As+DateTime,+daysSinceMonday+As+Integer
++++today+=+DateTime.Today
++++daysSinceMonday+=+today.DayOfWeek+-+DayOfWeek.Monday
++++If+daysSinceMonday+<+0+Then
++++++++daysSinceMonday+%2B=+7
++++End+If
++++Return+today.AddDays(-daysSinceMonday)++
End+Function|code-block|syntax|javascript|1411368|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|$]]

Following on from my comments to Meta-Knight's answer, here is a short function that makes the correction I mention in the comments:

<pre><code>Public Function GetFirstOfLastWeek() As DateTime
Dim today As DateTime, daysSinceMonday As Integer
 today = DateTime.Today
 daysSinceMonday = today.DayOfWeek - DayOfWeek.Monday
 If daysSinceMonday &lt; 0 Then
 daysSinceMonday += 7
 End If
 Return today.AddDays(-daysSinceMonday) 
End Function
</code></pre>

blocks|key|1411414|text|如果你的一周是从周一开始的，那么你可以这样使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1411415|DateTime+mondayDate+=+DateTime.Now.AddDays(((DateTime.Now.DayOfWeek+==+DayOfWeek.Sunday?7:+(int)DateTime.Now.DayOfWeek)+-+1)*-1);

DateTime+sundayDate+=+DateTime.Now.AddDays(7+-+(DateTime.Now.DayOfWeek+==+DayOfWeek.Sunday?7:+(int)DateTime.Now.DayOfWeek+));|code-block|syntax|javascript|1411416|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|$]]

And if your week starts from Monday then you can use something like this:

<pre><code>DateTime mondayDate = DateTime.Now.AddDays(((DateTime.Now.DayOfWeek == DayOfWeek.Sunday?7: (int)DateTime.Now.DayOfWeek) - 1)*-1);

DateTime sundayDate = DateTime.Now.AddDays(7 - (DateTime.Now.DayOfWeek == DayOfWeek.Sunday?7: (int)DateTime.Now.DayOfWeek ));
</code></pre>

I need to find a way to find the date (DD/MM/YYYY) of the Monday for any week we're on.

For example, for this week, monday would be 09/11/2009, and if this were next week it'd be 16/11/2009.

I managed to get somewhere in the forms of code, but all I got was 'cannot convert to Integer' errors. I was using Date.Today and AddDays().

Thanks for any help. :)

Finding the date of monday in a week with VB.NET

我需要找到一种方法来找到我们所在的任何一周的星期一的日期(DD/MM/YYYY)。例如，对于本周，星期一将是2009年9月11日，如果是下周，则是2009年16月11日。我设法以代码的形式得到了一些东西，但我得到的只是“无法转换为整数”的错误。我使用的是Date.Today和AddDays()。谢谢你的帮助。:)

问使用VB.NET查找一周内的星期一的日期
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