Re: Calculate diffrence between dates - weeks - but not so simple ...

[Booth Martin <booth@xxxxxxxxxxxx>]

What are you looking for?  the number of days, or the number of weeks?

Essentially,

    nbrDays = %diff(date2: date1: *days)
    nbrWeeks = (%diff(date2: date1: *days)) / 7

   // if the remainder is more than 3 days then add a week to the
     number of weeks.
     if (%rem(%diff(date2: date1: *days)) / 7) >= 4
     nbrWeeks = nbrWeeks + 1
     endif


Is that the sort of things you are looking for?

If the dividing line must be Saturday to Saturday the algorithm would 
change slightly.  Probably I would:

Get the day-of-week as a number. (Set the number so that Saturday = 0)
Find out what day-of-the-week date1 is, and add the inverse of that 
number of days to date1, then get the nbrDays / 7 and forget about the 
remainder.

      // Work fields
     D wTestDate       s               d   inz(d'2010-04-01')
     D wNdx            s             10i 0

          wNdx = %diff(date1: wTestDate: *days)
          wNdx = 7 - (%rem(wNdx: 7))
          date1 = date1 + %days(wNdx)
          nbrWeeks = (date2 - date1) / 7

(You may have to jiggle the inz(date) back or forward to get Saturday = 0.)

Or something like that,  If your two date fields are not real date 
fields, make them real date fields first.  Much easier.

http://www.martinvt.com/Code_Samples/Date_Math/date_math.html  Has a few 
various date math examples.


(I haven't tested this, so it may need some tapping and shoving to get 
what you want.)






> 2011/4/7 Tomasz Skorża<t.skorza@xxxxxxxxxxx>:
> > Hi
> >
> > I need to create an algorithm which allow me to calculate diffrence between two dates but assumption
> > is that first day of week is SATURDAY, and week going from saturday to friday.
> > So if first date is 2011-03-28 - monday, then for second date from 2011-03-29 to 2011-04-01
> > algorithm should return 1 (week), but for 2011-04-02 - saturday algorithm should return 2 (weeks).
> > Have you any idea?
> >
> > I tried many posssibilities and something is wrong, depend on start and stop dates sometimes result
> > is as I expect sometimes not ...
> >
> > Regards
> >
> > Tomek
> > --