Skip to content
⌘ NSIS Forum Archive

Here are 2 useful date functions

7 posts

fabiochelly#

Here are 2 useful date functions

I created 2 date functions: IsLeapYear and DaysInMonth:

To use it:
Push "year"
Call IsLeapYear
Pop $0 ;returns 0 or 1

Push "month"
Push "year"
Call DaysInMonth
Pop $0 ; returns 28, 29, 30 or 31 

Function IsLeapYear



  Pop $0

  IntOp $1 $0 % 4

  IntCmp $1 0 test2 ;si divisible par 4, on passe au test 2 (début de siècle)

  Goto ko ;sinon, retourne FAUX

  test2:

    IntOp $1 $0 % 100

    IntCmp $1 0 test3

    Goto ok

  test3:

    ;l'année est un siècle rond

    ;on vérifie si ce siècle est impair

    IntOp $1 $0 % 200

    IntCmp $1 0 ok

    Goto ko

  ok:

    Push 1

    Goto end

  ko:

    Push 0

  end:

FunctionEnd
Function DaysInMonth

  Pop $0 ;annee

  Pop $1 ;mois



  IntCmp $1 1 m31

  IntCmp $1 2 m28

  IntCmp $1 3 m31

  IntCmp $1 4 m30

  IntCmp $1 5 m31

  IntCmp $1 6 m30

  IntCmp $1 7 m31

  IntCmp $1 8 m31

  IntCmp $1 9 m30

  IntCmp $1 10 m31

  IntCmp $1 11 m30

  IntCmp $1 12 m31



  m31:

    Push 31

    Goto end

  m30:

    Push 30

    Goto end

  m28:

    Push $0

    Call IsLeapYear

    Pop $0

    IntCmp $0 1 m29

      Push 28

      Goto end

    m29:

     Push 29

  end:

FunctionEnd
deguix#
Maybe you based "Bissext" year from one of my functions, the correct name is "Leap" year.

And second, you can know if a year is a leap year using the simple calculation:

Year % 4

If the rest is 0, it is a leap year.

I should fix those two in my function but I didn't have time to do that.
fabiochelly#
Leap and not Bissext : corrected

No: Year / 4 is not enough : years 1700, 1900, 2100, 2300 (each 200 years) are not leap.

Effectively, I called it Bissext because I first tried to use your Seconds2Date function which doesn't work for me (see my other thread of this day)
Joost Verburg#
Fabiochelly is correct.

Every year divisible by 4 is a leap year.

However, every year divisible by 100 is not a leap year.
However, every year divisible by 400 is a leap year after all.

So, 1700, 1800, 1900, 2100, and 2200 are not leap years. But 1600, 2000, and 2400 are leap years.
fabiochelly#
see http://www.galactic-guide.com/articles/6R87.html

The explanation here:


or here:
http://www.timeanddate.com/date/leapyear.html

In fact:
1. Every year divisible by 4 is a leap year.
2. But every year divisible by 100 is NOT a leap year
3. Unless the year is also divisible by 400, then it is still a leap year.