[VBnet Helpers] Pure VB: Determining Leap Years


	Visual Basic Helper Routines Pure VB: Determining Leap Years

Posted:	Monday March 25, 2002
Updated:	Monday December 26, 2011

Applies to:	VB3, VB4-16, VB4-32, VB5, VB6
Developed with:	VB6, Windows NT4
OS restrictions:	None
Author:	Douglas Marquardt, Larry Serflaten

Related:	Pure VB: Methods to Determine the Last Day of the Month Pure VB: Methods to Determine Number of Days in a Month Pure VB: Determining Leap Years VarMonthName: Retrieve Localized Month Names VarWeekdayName: Retrieve Localized Weekday Names

Prerequisites

None.

In scouting the newsgroups I came across two simple non-API functions for determining whether a given year is a leap year. Provided by Douglas Marquardt and Larry Serflaten, they each take a different approach to arrive at the same conclusion. The choice is yours.

BAS Module Code

None.

Form Code

To a form, add a command button and the following code:

Option Explicit

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright ©1996-2011 VBnet/Randy Birch, All Rights Reserved.
' Some pages may also contain other copyrights by the author.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Distribution: You can freely use this code in your own
'               applications, but you may not reproduce 
'               or publish this code on any web site,
'               online service, or distribute as source 
'               on any media without express permission.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

Private Sub Command1_Click()

   Print 2000,
   Print IsLeapYearA(2000),
   Print IsLeapYearB(2000)
   
   Print 1999,
   Print IsLeapYearA(1999),
   Print IsLeapYearB(1999)
   
   Print 1998,
   Print IsLeapYearA(1998),
   Print IsLeapYearB(1998)
   
   Print 1997,
   Print IsLeapYearA(1997),
   Print IsLeapYearB(1997)
   
   Print 1996,
   Print IsLeapYearA(1996),
   Print IsLeapYearB(1996)
   
End Sub


Function IsLeapYearA(ByVal yr As Integer) As Boolean

  'Larry Serflaten
   If ((yr Mod 4) = 0) Then 
      IsLeapYearA = ((yr Mod 100) > 0) Or ((yr Mod 400) = 0)
   End If
   
End Function


Public Function IsLeapYearB(ByVal yr As Integer) As Boolean

  'Douglas Marquardt
   IsLeapYearB = Day(DateSerial(yr, 2, 29)) = 29
    
End Function

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