Artikel
11/18/2011

GregorianCalendar Class

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Represents the Gregorian calendar.

Inheritance Hierarchy

System.Object
System.Globalization.Calendar
System.Globalization.GregorianCalendar

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

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Class GregorianCalendar _
    Inherits Calendar

[ComVisibleAttribute(true)]
public class GregorianCalendar : Calendar

The GregorianCalendar type exposes the following members.

Constructors

	Name	Description
	GregorianCalendar()	Initializes a new instance of the GregorianCalendar class using the default GregorianCalendarTypes value.
	GregorianCalendar(GregorianCalendarTypes)	Initializes a new instance of the GregorianCalendar class using the specified GregorianCalendarTypes value.

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Properties

	Name	Description
	CalendarType	Gets or sets the GregorianCalendarTypes value that denotes the language version of the current GregorianCalendar.
	Eras	Gets the list of eras in the GregorianCalendar. (Overrides Calendar.Eras.)
	IsReadOnly	Gets a value indicating whether this Calendar object is read-only. (Inherited from Calendar.)
	MaxSupportedDateTime	Gets the latest date and time supported by the GregorianCalendar type. (Overrides Calendar.MaxSupportedDateTime.)
	MinSupportedDateTime	Gets the earliest date and time supported by the GregorianCalendar type. (Overrides Calendar.MinSupportedDateTime.)
	TwoDigitYearMax	Gets or sets the last year of a 100-year range that can be represented by a 2-digit year. (Overrides Calendar.TwoDigitYearMax.)

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Methods

	Name	Description
	AddDays	Returns a DateTime that is the specified number of days away from the specified DateTime. (Inherited from Calendar.)
	AddHours	Returns a DateTime that is the specified number of hours away from the specified DateTime. (Inherited from Calendar.)
	AddMilliseconds	Returns a DateTime that is the specified number of milliseconds away from the specified DateTime. (Inherited from Calendar.)
	AddMinutes	Returns a DateTime that is the specified number of minutes away from the specified DateTime. (Inherited from Calendar.)
	AddMonths	Returns a DateTime that is the specified number of months away from the specified DateTime. (Overrides Calendar.AddMonths(DateTime, Int32).)
	AddSeconds	Returns a DateTime that is the specified number of seconds away from the specified DateTime. (Inherited from Calendar.)
	AddWeeks	Returns a DateTime that is the specified number of weeks away from the specified DateTime. (Inherited from Calendar.)
	AddYears	Returns a DateTime that is the specified number of years away from the specified DateTime. (Overrides Calendar.AddYears(DateTime, Int32).)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetDayOfMonth	Returns the day of the month in the specified DateTime. (Overrides Calendar.GetDayOfMonth(DateTime).)
	GetDayOfWeek	Returns the day of the week in the specified DateTime. (Overrides Calendar.GetDayOfWeek(DateTime).)
	GetDayOfYear	Returns the day of the year in the specified DateTime. (Overrides Calendar.GetDayOfYear(DateTime).)
	GetDaysInMonth(Int32, Int32)	Returns the number of days in the specified month and year of the current era. (Inherited from Calendar.)
	GetDaysInMonth(Int32, Int32, Int32)	Returns the number of days in the specified month in the specified year in the specified era. (Overrides Calendar.GetDaysInMonth(Int32, Int32, Int32).)
	GetDaysInYear(Int32)	Returns the number of days in the specified year of the current era. (Inherited from Calendar.)
	GetDaysInYear(Int32, Int32)	Returns the number of days in the specified year in the specified era. (Overrides Calendar.GetDaysInYear(Int32, Int32).)
	GetEra	Returns the era of a specified DateTime value. (Overrides Calendar.GetEra(DateTime).)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetHour	Returns the hours value in the specified DateTime. (Inherited from Calendar.)
	GetLeapMonth	Calculates the leap month for a specified year and era. (Overrides Calendar.GetLeapMonth(Int32, Int32).)
	GetMilliseconds	Returns the milliseconds value in the specified DateTime. (Inherited from Calendar.)
	GetMinute	Returns the minutes value in the specified DateTime. (Inherited from Calendar.)
	GetMonth	Returns the month in the specified DateTime. (Overrides Calendar.GetMonth(DateTime).)
	GetMonthsInYear(Int32)	Returns the number of months in the specified year in the current era. (Inherited from Calendar.)
	GetMonthsInYear(Int32, Int32)	Returns the number of months in the specified year in the specified era. (Overrides Calendar.GetMonthsInYear(Int32, Int32).)
	GetSecond	Returns the seconds value in the specified DateTime. (Inherited from Calendar.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetWeekOfYear	Returns the week of the year that includes the date in the specified DateTime value. (Inherited from Calendar.) In Silverlight for Windows Phone, this member is overridden by GetWeekOfYear(DateTime, CalendarWeekRule, DayOfWeek). In XNA Framework, this member is overridden by GetWeekOfYear(DateTime, CalendarWeekRule, DayOfWeek).
	GetYear	Returns the year in the specified DateTime. (Overrides Calendar.GetYear(DateTime).)
	IsLeapDay(Int32, Int32, Int32)	Determines whether the specified date in the current era is a leap day. (Inherited from Calendar.)
	IsLeapDay(Int32, Int32, Int32, Int32)	Determines whether the specified date in the specified era is a leap day. (Overrides Calendar.IsLeapDay(Int32, Int32, Int32, Int32).)
	IsLeapMonth(Int32, Int32)	Determines whether the specified month in the specified year in the current era is a leap month. (Inherited from Calendar.)
	IsLeapMonth(Int32, Int32, Int32)	Determines whether the specified month in the specified year in the specified era is a leap month. (Overrides Calendar.IsLeapMonth(Int32, Int32, Int32).)
	IsLeapYear(Int32)	Determines whether the specified year in the current era is a leap year. (Inherited from Calendar.)
	IsLeapYear(Int32, Int32)	Determines whether the specified year in the specified era is a leap year. (Overrides Calendar.IsLeapYear(Int32, Int32).)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToDateTime(Int32, Int32, Int32, Int32, Int32, Int32, Int32)	Returns a DateTime that is set to the specified date and time in the current era. (Inherited from Calendar.)
	ToDateTime(Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32)	Returns a DateTime that is set to the specified date and time in the specified era. (Overrides Calendar.ToDateTime(Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32).)
	ToFourDigitYear	Converts the specified year to a four-digit year by using the TwoDigitYearMax property to determine the appropriate century. (Overrides Calendar.ToFourDigitYear(Int32).)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Fields

	Name	Description
	ADEra	Represents the current era. This field is constant.

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Remarks

The Gregorian calendar recognizes two eras: B.C. or B.C.E., and A.D. or C.E. This implementation of the GregorianCalendar class recognizes only the current era (A.D. or C.E.).

A leap year in the Gregorian calendar is defined as a year that is evenly divisible by four, except if it is divisible by 100. However, years that are divisible by 400 are leap years. For example, the year 1900 was not a leap year, but the year 2000 was. A common year has 365 days and a leap year has 366 days.

The Gregorian calendar has 12 months with 28 to 31 days each: January (31 days), February (28 or 29 days), March (31 days), April (30 days), May (31 days), June (30 days), July (31 days), August (31 days), September (30 days), October (31 days), November (30 days), and December (31 days). February has 29 days during leap years and 28 during common years.

Each CultureInfo object supports a set of calendars. The CultureInfo.Calendar property returns the default calendar for the culture, and the CultureInfo.OptionalCalendars property returns an array containing all the calendars supported by the culture. To change the calendar used by a CultureInfo object, the application can set the DateTimeFormatInfo.Calendar property to a new Calendar object if the new calendar is one of the culture's optional calendars. The following example shows how to change the calendar for the th-TH culture to the Gregorian calendar.

' Change the calendar used by a th-TH CultureInfo object from ThaiBuddhist to Gregorian. 
Dim thaiCulture As New CultureInfo("th-TH")
Dim originalCalendar As Calendar = thaiCulture.Calendar
Dim message As String = Nothing

' Confirm that the default calendar is not the Japanese calendar.
If originalCalendar.ToString <> "System.Globalization.GregorianCalendar" Then
   ' Check whether the culture supports the Gregorian calendar.
   Dim supported As Boolean = False
   For Each supportedCal As Calendar In thaiCulture.OptionalCalendars
      If supportedCal.ToString = "System.Globalization.GregorianCalendar" Then
         supported = True            
         thaiCulture.DateTimeFormat.Calendar = supportedCal
         message = String.Format("Changed the current calendar for the {0} culture from {1} to {2}.", _
                                 thaiCulture.ToString(), _
                                 originalCalendar.ToString.Replace("System.Globalization.", ""), _
                                 supportedCal.ToString.Replace("System.Globalization.", ""))                                 
         Exit For
      End If
      If Not supported Then message = "The Gregorian calendar is not supported."
   Next        
Else
   message = String.Format("Gregorian is the default calendar for the {0} culture.", _
                           thaiCulture.ToString())
End If
outputBlock.Text += message + vbCrLf
' The example displays the following output:
'   Changed the current calendar for the ja-JP culture from GregorianCalendar to JapaneseCalendar.

// Change the calendar used by a th-TH CultureInfo object from ThaiBuddhist to Gregorian. 
CultureInfo thaiCulture = new CultureInfo("th-TH");
Calendar originalCalendar = thaiCulture.Calendar;
string message = null;

// Confirm that the default calendar is not the Japanese calendar.
if (originalCalendar.ToString() != "System.Globalization.GregorianCalendar")
{
   // Check whether the culture supports the Gregorian calendar.
   bool supported = false;
   foreach (Calendar supportedCal in thaiCulture.OptionalCalendars)
   {
      if (supportedCal.ToString() == "System.Globalization.GregorianCalendar")
      {
         supported = true;            
         thaiCulture.DateTimeFormat.Calendar = supportedCal;
         message = String.Format("Changed the current calendar for the {0} culture from {1} to {2}.", 
                                 thaiCulture.ToString(), 
                                 originalCalendar.ToString().Replace("System.Globalization.", ""), 
                                 supportedCal.ToString().Replace("System.Globalization.", ""));                                 
         break;
      }
   }        
   if (! supported) message = "The Gregorian calendar is not supported.";
}
else
{
   message = String.Format("Gregorian is the default calendar for the {0} culture.",
                           thaiCulture.ToString());
}
outputBlock.Text += message + "\n";
// The example displays the following output:
//   Changed the current calendar for the ja-JP culture from GregorianCalendar to JapaneseCalendar.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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