Re: Bug in IBM Date Routies %month -- RPG400-L


On 29/03/2006, at 12:26 PM, praveen gunda wrote:

my simple question is:

1 + 1 + 1 => 3 <= 2  + 1

but

Date + %months(2)  is not equal to Date + %months(1) + %months(1)

Here date need not always be the end of month.

Actually it does have to be the end (or at least the last few days)otherwise you won't see this so-called problem.


Eg: 2006-01-30 is not End Of Month

2006-01-30 + %months(2) = 2006-03-31


Not in RPG IV. 2006-01-30 + %months(2) = 2006-03-30

but 2006-01-30 + %months(1) + %months(1) is not equal to 2006-03-31


In RPG IV the answer is 2006-03-28 due to intermediate results:
                2006-01-30
        plus     01
        =   2006-02-28
        plus     01
        =   2006-03-28

Don't know why you're complaining. It's documented behaviour. You saidpreviously that you "never had this problem with Java" but I can provethat Java behaves "inconsistently" too.


import java.util.*;
public class PraveenCalendar2
{
  public static void main(String[] args)
  {
    GregorianCalendar gc1 = new GregorianCalendar(2006, 0, 30);
    GregorianCalendar gc2 = new GregorianCalendar(2006, 0, 30);

    System.out.println(gc1.getTime());
    gc1.add(Calendar.MONTH, 1);
    System.out.println(gc1.getTime());
    gc1.add(Calendar.MONTH, 1);
    System.out.println(gc1.getTime());
    System.out.println("");
    System.out.println(gc2.getTime());
    gc2.add(Calendar.MONTH, 2);
    System.out.println(gc2.getTime());

}}


 > java  PraveenCalendar2
   Mon Jan 30 00:00:00 GMT 2006
   Tue Feb 28 00:00:00 GMT 2006
   Tue Mar 28 00:00:00 GMT 2006

   Mon Jan 30 00:00:00 GMT 2006
   Thu Mar 30 00:00:00 GMT 2006

You can see that:
        Date + month(1) + month(1) <> Date + month(2)

However both RPG IV and Java provide the same dates for the samecalculation.:

        Date = 2006-01-30
        Date + month(1) + month(1)      = 2006-03-28
        Date + month(2)                         = 2006-03-30

Consistent results is what is important even if they don't fit yourview of "correct".

I don't know why I'm bothering with this topic anyway ... it's inane.Date maths is not arithmetic--it has it's own set of rules, nor is itreciprocal:

        2006-01-31 + %month(1) - %month(1) <> 2006-01-31

Accept the behaviour and move on.

Regards,
Simon Coulter.
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