# Calendar.IsLeapDay Method

## Definition

When overridden in a derived class, determines whether a date is a leap day.

 IsLeapDay(Int32, Int32, Int32) Determines whether the specified date in the current era is a leap day. IsLeapDay(Int32, Int32, Int32, Int32) When overridden in a derived class, determines whether the specified date in the specified era is a leap day.

## IsLeapDay(Int32, Int32, Int32)

Determines whether the specified date in the current era is a leap day.

public:
virtual bool IsLeapDay(int year, int month, int day);
public virtual bool IsLeapDay (int year, int month, int day);
abstract member IsLeapDay : int * int * int -> bool
override this.IsLeapDay : int * int * int -> bool
Public Overridable Function IsLeapDay (year As Integer, month As Integer, day As Integer) As Boolean

#### Parameters

year
Int32

An integer that represents the year.

month
Int32

A positive integer that represents the month.

day
Int32

A positive integer that represents the day.

#### Returns

Boolean

true if the specified day is a leap day; otherwise, false.

#### Exceptions

year is outside the range supported by the calendar.

-or-

month is outside the range supported by the calendar.

-or-

day is outside the range supported by the calendar.

### Examples

The following code example compares different implementations of the Calendar class.

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

// Creates an instance of every Calendar type.
array<Calendar^>^myCals = gcnew array<Calendar^>(8);
myCals[ 0 ] = gcnew GregorianCalendar;
myCals[ 1 ] = gcnew HebrewCalendar;
myCals[ 2 ] = gcnew HijriCalendar;
myCals[ 3 ] = gcnew JapaneseCalendar;
myCals[ 4 ] = gcnew JulianCalendar;
myCals[ 5 ] = gcnew KoreanCalendar;
myCals[ 6 ] = gcnew TaiwanCalendar;
myCals[ 7 ] = gcnew ThaiBuddhistCalendar;

// For each calendar, displays the current year, the number of months in that year,
// and the number of days in each month of that year.
int i;
int j;
int iYear;
int iMonth;
int iDay;
DateTime myDT = DateTime::Today;
for ( i = 0; i < myCals->Length; i++ )
{
iYear = myCals[ i ]->GetYear( myDT );
Console::WriteLine();
Console::WriteLine( " {0}, Year: {1}", myCals[ i ]->GetType(), myCals[ i ]->GetYear( myDT ) );
Console::WriteLine( "   MonthsInYear: {0}", myCals[ i ]->GetMonthsInYear( iYear ) );
Console::WriteLine( "   DaysInYear: {0}", myCals[ i ]->GetDaysInYear( iYear ) );
Console::WriteLine( "   Days in each month:" );
Console::Write( "      " );
for ( j = 1; j <= myCals[ i ]->GetMonthsInYear( iYear ); j++ )
Console::Write( " {0, -5}", myCals[ i ]->GetDaysInMonth( iYear, j ) );
Console::WriteLine();
iMonth = myCals[ i ]->GetMonth( myDT );
iDay = myCals[ i ]->GetDayOfMonth( myDT );
Console::WriteLine( "   IsLeapDay: {0}", myCals[ i ]->IsLeapDay( iYear, iMonth, iDay ) );
Console::WriteLine( "   IsLeapMonth: {0}", myCals[ i ]->IsLeapMonth( iYear, iMonth ) );
Console::WriteLine( "   IsLeapYear: {0}", myCals[ i ]->IsLeapYear( iYear ) );

}
}

/*
This code produces the following output.  The results vary depending on the date.

System::Globalization::GregorianCalendar, Year: 2002
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System::Globalization::HebrewCalendar, Year: 5763
MonthsInYear: 13
DaysInYear: 385
Days in each month:
30    30    30    29    30    30    29    30    29    30    29    30    29
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  True

System::Globalization::HijriCalendar, Year: 1423
MonthsInYear: 12
DaysInYear: 355
Days in each month:
30    29    30    29    30    29    30    29    30    29    30    30
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  True

System::Globalization::JapaneseCalendar, Year: 14
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System::Globalization::JulianCalendar, Year: 2002
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System::Globalization::KoreanCalendar, Year: 4335
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System::Globalization::TaiwanCalendar, Year: 91
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System::Globalization::ThaiBuddhistCalendar, Year: 2545
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

*/
using System;
using System.Globalization;

public class SamplesCalendar  {

public static void Main()  {

// Creates an instance of every Calendar type.
Calendar[] myCals = new Calendar[8];
myCals[0] = new GregorianCalendar();
myCals[1] = new HebrewCalendar();
myCals[2] = new HijriCalendar();
myCals[3] = new JapaneseCalendar();
myCals[4] = new JulianCalendar();
myCals[5] = new KoreanCalendar();
myCals[6] = new TaiwanCalendar();
myCals[7] = new ThaiBuddhistCalendar();

// For each calendar, displays the current year, the number of months in that year,
// and the number of days in each month of that year.
int i, j, iYear, iMonth, iDay;
DateTime myDT = DateTime.Today;

for ( i = 0; i < myCals.Length; i++ )  {
iYear = myCals[i].GetYear( myDT );
Console.WriteLine();
Console.WriteLine( "{0}, Year: {1}", myCals[i].GetType(), myCals[i].GetYear( myDT ) );
Console.WriteLine( "   MonthsInYear: {0}", myCals[i].GetMonthsInYear( iYear ) );
Console.WriteLine( "   DaysInYear: {0}", myCals[i].GetDaysInYear( iYear ) );
Console.WriteLine( "   Days in each month:" );
Console.Write( "      " );

for ( j = 1; j <= myCals[i].GetMonthsInYear( iYear ); j++ )
Console.Write( " {0,-5}", myCals[i].GetDaysInMonth( iYear, j ) );
Console.WriteLine();

iMonth = myCals[i].GetMonth( myDT );
iDay = myCals[i].GetDayOfMonth( myDT );
Console.WriteLine( "   IsLeapDay:   {0}", myCals[i].IsLeapDay( iYear, iMonth, iDay ) );
Console.WriteLine( "   IsLeapMonth: {0}", myCals[i].IsLeapMonth( iYear, iMonth ) );
Console.WriteLine( "   IsLeapYear:  {0}", myCals[i].IsLeapYear( iYear ) );
}
}
}

/*
This code produces the following output.  The results vary depending on the date.

System.Globalization.GregorianCalendar, Year: 2002
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System.Globalization.HebrewCalendar, Year: 5763
MonthsInYear: 13
DaysInYear: 385
Days in each month:
30    30    30    29    30    30    29    30    29    30    29    30    29
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  True

System.Globalization.HijriCalendar, Year: 1423
MonthsInYear: 12
DaysInYear: 355
Days in each month:
30    29    30    29    30    29    30    29    30    29    30    30
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  True

System.Globalization.JapaneseCalendar, Year: 14
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System.Globalization.JulianCalendar, Year: 2002
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System.Globalization.KoreanCalendar, Year: 4335
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System.Globalization.TaiwanCalendar, Year: 91
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

System.Globalization.ThaiBuddhistCalendar, Year: 2545
MonthsInYear: 12
DaysInYear: 365
Days in each month:
31    28    31    30    31    30    31    31    30    31    30    31
IsLeapDay:   False
IsLeapMonth: False
IsLeapYear:  False

*/
Imports System.Globalization

Public Class SamplesCalendar

Public Shared Sub Main()

' Creates an instance of every Calendar type.
Dim myCals(7) As Calendar
myCals(0) = New GregorianCalendar()
myCals(1) = New HebrewCalendar()
myCals(2) = New HijriCalendar()
myCals(3) = New JapaneseCalendar()
myCals(4) = New JulianCalendar()
myCals(5) = New KoreanCalendar()
myCals(6) = New TaiwanCalendar()
myCals(7) = New ThaiBuddhistCalendar()

' For each calendar, displays the current year, the number of months in that year,
' and the number of days in each month of that year.
Dim i, j, iYear, iMonth, iDay As Integer
Dim myDT As DateTime = DateTime.Today

For i = 0 To myCals.Length - 1
iYear = myCals(i).GetYear(myDT)
Console.WriteLine()
Console.WriteLine("{0}, Year: {1}", myCals(i).GetType(), myCals(i).GetYear(myDT))
Console.WriteLine("   MonthsInYear: {0}", myCals(i).GetMonthsInYear(iYear))
Console.WriteLine("   DaysInYear: {0}", myCals(i).GetDaysInYear(iYear))
Console.WriteLine("   Days in each month:")
Console.Write("      ")

For j = 1 To myCals(i).GetMonthsInYear(iYear)
Console.Write(" {0,-5}", myCals(i).GetDaysInMonth(iYear, j))
Next j
Console.WriteLine()

iMonth = myCals(i).GetMonth(myDT)
iDay = myCals(i).GetDayOfMonth(myDT)
Console.WriteLine("   IsLeapDay:   {0}", myCals(i).IsLeapDay(iYear, iMonth, iDay))
Console.WriteLine("   IsLeapMonth: {0}", myCals(i).IsLeapMonth(iYear, iMonth))
Console.WriteLine("   IsLeapYear:  {0}", myCals(i).IsLeapYear(iYear))
Next i

End Sub

End Class

'This code produces the following output.  The results vary depending on the date.
'
'System.Globalization.GregorianCalendar, Year: 2002
'   MonthsInYear: 12
'   DaysInYear: 365
'   Days in each month:
'       31    28    31    30    31    30    31    31    30    31    30    31
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  False
'
'System.Globalization.HebrewCalendar, Year: 5763
'   MonthsInYear: 13
'   DaysInYear: 385
'   Days in each month:
'       30    30    30    29    30    30    29    30    29    30    29    30    29
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  True
'
'System.Globalization.HijriCalendar, Year: 1423
'   MonthsInYear: 12
'   DaysInYear: 355
'   Days in each month:
'       30    29    30    29    30    29    30    29    30    29    30    30
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  True
'
'System.Globalization.JapaneseCalendar, Year: 14
'   MonthsInYear: 12
'   DaysInYear: 365
'   Days in each month:
'       31    28    31    30    31    30    31    31    30    31    30    31
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  False
'
'System.Globalization.JulianCalendar, Year: 2002
'   MonthsInYear: 12
'   DaysInYear: 365
'   Days in each month:
'       31    28    31    30    31    30    31    31    30    31    30    31
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  False
'
'System.Globalization.KoreanCalendar, Year: 4335
'   MonthsInYear: 12
'   DaysInYear: 365
'   Days in each month:
'       31    28    31    30    31    30    31    31    30    31    30    31
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  False
'
'System.Globalization.TaiwanCalendar, Year: 91
'   MonthsInYear: 12
'   DaysInYear: 365
'   Days in each month:
'       31    28    31    30    31    30    31    31    30    31    30    31
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  False
'
'System.Globalization.ThaiBuddhistCalendar, Year: 2545
'   MonthsInYear: 12
'   DaysInYear: 365
'   Days in each month:
'       31    28    31    30    31    30    31    31    30    31    30    31
'   IsLeapDay:   False
'   IsLeapMonth: False
'   IsLeapYear:  False

### Remarks

To make up for the difference between the calendar year and the actual time that the earth rotates around the sun or the actual time that the moon rotates around the earth, a leap year has a different number of days from a standard calendar year. Each Calendar implementation defines leap years differently.

A leap day is a day that occurs only in a leap year. For example, in the Gregorian calendar, the 29th day of February is the only leap day.

## IsLeapDay(Int32, Int32, Int32, Int32)

When overridden in a derived class, determines whether the specified date in the specified era is a leap day.

public:
abstract bool IsLeapDay(int year, int month, int day, int era);
public abstract bool IsLeapDay (int year, int month, int day, int era);
abstract member IsLeapDay : int * int * int * int -> bool
Public MustOverride Function IsLeapDay (year As Integer, month As Integer, day As Integer, era As Integer) As Boolean

#### Parameters

year
Int32

An integer that represents the year.

month
Int32

A positive integer that represents the month.

day
Int32

A positive integer that represents the day.

era
Int32

An integer that represents the era.

#### Returns

Boolean

true if the specified day is a leap day; otherwise, false.

#### Exceptions

year is outside the range supported by the calendar.

-or-

month is outside the range supported by the calendar.

-or-

day is outside the range supported by the calendar.

-or-

era is outside the range supported by the calendar.

### Remarks

To make up for the difference between the calendar year and the actual time that the earth rotates around the sun or the actual time that the moon rotates around the earth, a leap year has a different number of days from a standard calendar year. Each Calendar implementation defines leap years differently.

A leap day is a day that occurs only in a leap year. For example, in the Gregorian calendar, the 29th day of February is the only leap day.

### Notes to Implementers

The derived class must support CurrentEra when it is passed as the era parameter. One way to support CurrentEra is by replacing it with the value stored in Eras[0], which is the value for the current era of the calendar.