[Lazarus] DateDif function needed

[Michael Van Canneyt]

On Fri, 15 Nov 2013, Bart wrote:

> On 11/15/13, Michael Schnell <mschnell at lumino.de> wrote:
>
>> In fact I consider it a waste of bandwidth to discuss a problem that
>> obviously is not solvable at this length. (But who am I do complain
>> about that :-[ .)
>>
>
> Of course it can be solved.
> Just add a enough options (appr. 255?) to the procedure to make it
> behave just like the caller wants.
> Do I want to do that? No.  ;-)
>
> The fun part for me is the fact that a seemingly simple question,
> where at first glance you would think "I'll just implement that", can
> lead to so many "problems".

I added a modified version of your implementation to the DateUtils unit as:

Procedure PeriodBetween(Const ANow, AThen: TDateTime; Out Years, months, days : Word);

I chose this name because it is more in line with the existing XXXBetween functions.

I did change the algorithm so it does not do the correction for february of the leap year.
It returns now the same results as the Jedi function. (which I didn't take for license reasons)

Thanks for providing an implementation.

Michael.