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DateTime extension method to give Week number

, 8 Sep 2011
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Here another approach taken from my article Time Period Library for .NET[^], which returns addditional the year of the week.// ------------------------------------------------------------------------public enum YearWeekType{ Calendar, Iso8601,} // enum YearWeekType //...
Here another approach taken from my article Time Period Library for .NET[^], which returns addditional the year of the week.
// ------------------------------------------------------------------------
public enum YearWeekType
{
  Calendar,
  Iso8601,
} // enum YearWeekType
  
// ------------------------------------------------------------------------
public static class TimeTool
{
 
  // ----------------------------------------------------------------------
  public static void GetWeekOfYear( DateTime moment, YearWeekType yearWeekType,
    out int year, out int weekOfYear )
  {
    GetWeekOfYear( moment, Thread.CurrentThread.CurrentCulture, yearWeekType, out year, out weekOfYear );
  } // GetWeekOfYear

  // ----------------------------------------------------------------------
  public static void GetWeekOfYear( DateTime moment, CultureInfo culture, YearWeekType yearWeekType,
    out int year, out int weekOfYear )
  {
    GetWeekOfYear( moment, culture, culture.DateTimeFormat.CalendarWeekRule, culture.DateTimeFormat.FirstDayOfWeek, yearWeekType,
      out year, out weekOfYear );
  } // GetWeekOfYear

  // ----------------------------------------------------------------------
  public static void GetWeekOfYear( DateTime moment, CultureInfo culture,
    CalendarWeekRule weekRule, DayOfWeek firstDayOfWeek, YearWeekType yearWeekType, out int year, out int weekOfYear )
  {
    if ( culture == null )
    {
      throw new ArgumentNullException( "culture" );
    }
 
    if ( yearWeekType == YearWeekType.Iso8601 && weekRule == CalendarWeekRule.FirstFourDayWeek && firstDayOfWeek == DayOfWeek.Monday )
    {
      DayOfWeek day = culture.Calendar.GetDayOfWeek( moment );
      if ( day >= DayOfWeek.Monday && day <= DayOfWeek.Wednesday )
      {
        moment = moment.AddDays( 3 );
      }
    }
 
    weekOfYear = culture.Calendar.GetWeekOfYear( moment, weekRule, firstDayOfWeek );
    year = moment.Year;
    if ( weekOfYear >= 52 && moment.Month < 12 )
    {
      year--;
    }
  } // GetWeekOfYear

} // class TimeTool

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Jani Giannoudis
Software Developer (Senior)
Switzerland Switzerland
Jani is Co-founder of Meerazo.com, a free service which allows to share resources like locations, things, persons and their services in a cooperating group of people.

Comments and Discussions

 
General+5 - Your time period lib is a seminal piece of work I would... PinmemberReiss8-Sep-11 4:55 
GeneralRe: Many thanks :) PinmvpJani Giannoudis8-Sep-11 5:08 

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