DateTime.IsLeapYear(Int32) Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

DateTime.cs

Returns an indication whether the specified year is a leap year.

public:
 static bool IsLeapYear(int year);

public static bool IsLeapYear (int year);

static member IsLeapYear : int -> bool

Public Shared Function IsLeapYear (year As Integer) As Boolean

Parameters

year

Int32

A 4-digit year.

Returns

Boolean

true if year is a leap year; otherwise, false.

Exceptions

ArgumentOutOfRangeException

year is less than 1 or greater than 9999.

Examples

The following example uses the IsLeapYear method to determine which years between 1994 and 2014 are leap years. The example also illustrates the result when the AddYears method is used to add a year to a leap day.

using System;

public class IsLeapYear
{
   public static void Main()
   {
      for (int year = 1994; year <= 2014; year++)
      {
         if (DateTime.IsLeapYear(year))
         {
            Console.WriteLine("{0} is a leap year.", year);
            DateTime leapDay = new DateTime(year, 2, 29);
            DateTime nextYear = leapDay.AddYears(1);
            Console.WriteLine("   One year from {0} is {1}.",
                              leapDay.ToString("d"),
                              nextYear.ToString("d"));
         }
      }
   }
}
// The example produces the following output:
//       1996 is a leap year.
//          One year from 2/29/1996 is 2/28/1997.
//       2000 is a leap year.
//          One year from 2/29/2000 is 2/28/2001.
//       2004 is a leap year.
//          One year from 2/29/2004 is 2/28/2005.
//       2008 is a leap year.
//          One year from 2/29/2008 is 2/28/2009.
//       2012 is a leap year.
//          One year from 2/29/2012 is 2/28/2013.

open System

[ 1994..2014 ]
|> List.filter DateTime.IsLeapYear
|> List.iter (fun year ->
    printfn $"{year} is a leap year."
    let leapDay = DateTime(year, 2, 29)
    let nextYear = leapDay.AddYears 1
    printfn $"   One year from {leapDay:d} is {nextYear:d}.")

// The example produces the following output:
//       1996 is a leap year.
//          One year from 2/29/1996 is 2/28/1997.
//       2000 is a leap year.
//          One year from 2/29/2000 is 2/28/2001.
//       2004 is a leap year.
//          One year from 2/29/2004 is 2/28/2005.
//       2008 is a leap year.
//          One year from 2/29/2008 is 2/28/2009.
//       2012 is a leap year.
//          One year from 2/29/2012 is 2/28/2013.

Module IsLeapYear
   Public Sub Main()
      For year As Integer = 1994 to 2014
         If DateTime.IsLeapYear(year) Then
            Console.WriteLine("{0} is a leap year.", year)
            Dim leapDay As New Date(year, 2, 29)
            Dim nextYear As Date = leapDay.AddYears(1)
            Console.WriteLine("   One year from {0} is {1}.", _
                              leapDay.ToString("d"), _
                              nextYear.ToString("d"))
         End If
      Next
   End Sub
End Module
' The example displays the following output:
'       1996 is a leap year.
'          One year from 2/29/1996 is 2/28/1997.
'       2000 is a leap year.
'          One year from 2/29/2000 is 2/28/2001.
'       2004 is a leap year.
'          One year from 2/29/2004 is 2/28/2005.
'       2008 is a leap year.
'          One year from 2/29/2008 is 2/28/2009.
'       2012 is a leap year.
'          One year from 2/29/2012 is 2/28/2013.

Remarks

year is specified as a 4-digit base 10 number; for example, 1996.

year is always interpreted as a year in the Gregorian calendar. To determine whether a particular year was a leap year in some other calendar, call that calendar object's IsLeapYear method.