Calendar.GetWeekOfYear Method (System.Globalization)

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GetWeekOfYear Method

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Microsoft Visual Studio 2008/.NET Framework 3.5

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.NET Framework Class Library

Calendar..::.GetWeekOfYear Method

Returns the week of the year that includes the date in the specified DateTime.

Namespace: System.Globalization
Assembly: mscorlib (in mscorlib.dll)

Syntax

Visual Basic (Declaration)

Public Overridable Function GetWeekOfYear ( _
    time As DateTime, _
    rule As CalendarWeekRule, _
    firstDayOfWeek As DayOfWeek _
) As Integer

Visual Basic (Usage)

Dim instance As Calendar
Dim time As DateTime
Dim rule As CalendarWeekRule
Dim firstDayOfWeek As DayOfWeek
Dim returnValue As Integer

returnValue = instance.GetWeekOfYear(time, _
    rule, firstDayOfWeek)

public virtual int GetWeekOfYear(
    DateTime time,
    CalendarWeekRule rule,
    DayOfWeek firstDayOfWeek
)

Visual C++

public:
virtual int GetWeekOfYear(
    DateTime time, 
    CalendarWeekRule rule, 
    DayOfWeek firstDayOfWeek
)

JScript

public function GetWeekOfYear(
    time : DateTime, 
    rule : CalendarWeekRule, 
    firstDayOfWeek : DayOfWeek
) : int

Parameters

time: Type: System..::.DateTime
The DateTime to read.

rule: Type: System.Globalization..::.CalendarWeekRule
A CalendarWeekRule value that defines a calendar week.

firstDayOfWeek: Type: System..::.DayOfWeek
A DayOfWeek value that represents the first day of the week.

Return Value

Type: System..::.Int32
A positive integer that represents the week of the year that includes the date in the time parameter.

Exceptions

Exception	Condition
ArgumentOutOfRangeException	firstDayOfWeek is outside the range supported by the calendar. -or- rule is not a valid CalendarWeekRule value.

Exception

Condition

ArgumentOutOfRangeException

firstDayOfWeek is outside the range supported by the calendar.

-or-

rule is not a valid CalendarWeekRule value.

Remarks

This method can be used to determine the number of weeks in the year by setting time to the last day of the year.

The CultureInfo..::.DateTimeFormat property contains culture-specific values that can be used for rule and firstDayOfWeek.

The FirstDayOfWeek property contains the default DayOfWeek value that represents the first day of the week for a specific culture, using the calendar specified in the Calendar property.

The CalendarWeekRule property contains the default CalendarWeekRule value that defines a calendar week for a specific culture, using the calendar specified in the Calendar property.

For example, in GregorianCalendar, the GetWeekOfYear method for January 1 returns 1.

Examples

The following code example shows how the result of GetWeekOfYear varies depending on the FirstDayOfWeek and the CalendarWeekRule used. If the specified date is the last day of the year, GetWeekOfYear returns the total number of weeks in that year.

Visual Basic

Imports System
Imports System.Globalization

Public Class SamplesCalendar

   Public Shared Sub Main()

      ' Gets the Calendar instance associated with a CultureInfo.
      Dim myCI As New CultureInfo("en-US")
      Dim myCal As Calendar = myCI.Calendar

      ' Gets the DTFI properties required by GetWeekOfYear.
      Dim myCWR As CalendarWeekRule = myCI.DateTimeFormat.CalendarWeekRule
      Dim myFirstDOW As DayOfWeek = myCI.DateTimeFormat.FirstDayOfWeek

      ' Displays the number of the current week relative to the beginning of the year.
      Console.WriteLine("The CalendarWeekRule used for the en-US culture is {0}.", myCWR)
      Console.WriteLine("The FirstDayOfWeek used for the en-US culture is {0}.", myFirstDOW)
      Console.WriteLine("Therefore, the current week is Week {0} of the current year.", myCal.GetWeekOfYear(DateTime.Now, myCWR, myFirstDOW))

      ' Displays the total number of weeks in the current year.
      Dim LastDay = New System.DateTime(DateTime.Now.Year, 12, 31)
      Console.WriteLine("There are {0} weeks in the current year ({1}).", myCal.GetWeekOfYear(LastDay, myCWR, myFirstDOW), LastDay.Year)
   End Sub 'Main 
End Class 'SamplesCalendar


'This code produces the following output.  Results vary depending on the system date.
'
'The CalendarWeekRule used for the en-US culture is FirstDay.
'The FirstDayOfWeek used for the en-US culture is Sunday.
'Therefore, the current week is Week 1 of the current year.
'There are 53 weeks in the current year (2001).

using System;
using System.Globalization;


public class SamplesCalendar  {

   public static void Main()  {

      // Gets the Calendar instance associated with a CultureInfo.
      CultureInfo myCI = new CultureInfo("en-US");
      Calendar myCal = myCI.Calendar;

      // Gets the DTFI properties required by GetWeekOfYear.
      CalendarWeekRule myCWR = myCI.DateTimeFormat.CalendarWeekRule;
      DayOfWeek myFirstDOW = myCI.DateTimeFormat.FirstDayOfWeek;

      // Displays the number of the current week relative to the beginning of the year.
      Console.WriteLine( "The CalendarWeekRule used for the en-US culture is {0}.", myCWR );
      Console.WriteLine( "The FirstDayOfWeek used for the en-US culture is {0}.", myFirstDOW );
      Console.WriteLine( "Therefore, the current week is Week {0} of the current year.", myCal.GetWeekOfYear( DateTime.Now, myCWR, myFirstDOW ));

      // Displays the total number of weeks in the current year.
      DateTime LastDay = new System.DateTime( DateTime.Now.Year, 12, 31 );
      Console.WriteLine( "There are {0} weeks in the current year ({1}).", myCal.GetWeekOfYear( LastDay, myCWR, myFirstDOW ), LastDay.Year );

   }

}

/*
This code produces the following output.  Results vary depending on the system date.

The CalendarWeekRule used for the en-US culture is FirstDay.
The FirstDayOfWeek used for the en-US culture is Sunday.
Therefore, the current week is Week 1 of the current year.
There are 53 weeks in the current year (2001).

*/

Visual C++

using namespace System;
using namespace System::Globalization;
int main()
{

   // Gets the Calendar instance associated with a CultureInfo.
   CultureInfo^ myCI = gcnew CultureInfo( "en-US" );
   Calendar^ myCal = myCI->Calendar;

   // Gets the DTFI properties required by GetWeekOfYear.
   CalendarWeekRule myCWR = myCI->DateTimeFormat->CalendarWeekRule;
   DayOfWeek myFirstDOW = myCI->DateTimeFormat->FirstDayOfWeek;

   // Displays the number of the current week relative to the beginning of the year.
   Console::WriteLine( "The CalendarWeekRule used for the en-US culture is {0}.", myCWR );
   Console::WriteLine( "The FirstDayOfWeek used for the en-US culture is {0}.", myFirstDOW );
   Console::WriteLine( "Therefore, the current week is Week {0} of the current year.", myCal->GetWeekOfYear( DateTime::Now, myCWR, myFirstDOW ) );

   // Displays the total number of weeks in the current year.
   DateTime LastDay = System::DateTime( DateTime::Now.Year, 12, 31 );
   Console::WriteLine( "There are {0} weeks in the current year ( {1}).", myCal->GetWeekOfYear( LastDay, myCWR, myFirstDOW ), LastDay.Year );
}

/*
This code produces the following output.  Results vary depending on the system date.

The CalendarWeekRule used for the en-US culture is FirstDay.
The FirstDayOfWeek used for the en-US culture is Sunday.
Therefore, the current week is Week 1 of the current year.
There are 53 weeks in the current year (2001).
*/

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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