Or an ICASE? (I haven't quite wrapped my head around what you're doing there but it seems like there are 3 states?)
m.theOffset=ICASE(theDiff>3, 7-m.theDiff,theDiff<-3, 7+m.theDiff, m.theDiff)
--
rk
-----Original Message----- From: ProfoxTech profoxtech-bounces@leafe.com On Behalf Of Ted Roche Sent: Tuesday, May 08, 2018 3:25 PM To: profoxtech@leafe.com Subject: Re: Fun with date calculations in VFP
GOMONTH() just moves back to 2/28 on years that don't have a 2/29, so your olddate({^2016-02-29},-2) gives you the previous Tuesday, 2/24/2014.
Hmmm. That's an OBO. It goes back 4 instead of forward 3. I think the nearest date ought to be 2014-03-03
Ah, if thediff = -4, it remains -4. That's a bug. Add the second line below after the first:
m.theOffset=IIF(theDiff>3, 7-m.theDiff, m.theDiff) m.theOffset=IIF(theDiff<-3, 7+m.theDiff, m.theDiff)
I know there's a better algorithm, likely involving MOD() or CEILING() or FLOOR() but it's escaping me at the moment.
There's 49 combinations of original date = (1,2,3,4,5,6,7) and resultant date = (1,2,3,4,5,6,7) and the offset should come out as {-3,-2,-1,0,1,2,3} , but I'm drawing a blank. Anyone? Beuller?
On Tue, May 8, 2018 at 2:15 PM, Richard Kaye rkaye@invaluable.com wrote:
Ted's solution works just fine. What I didn't test yet is using leap day itself as the starting point. Hmmm.....
Program: datestuff3.prgDate: 05/08/2018 11:09 AM- VFP Version: Visual FoxPro 09.00.0000.7423 for Windows
Notes:
ACTIVATE SCREEN CLEAR ? [Today: ]+CHR(9)+CHR(9) ?? DATE() ?? CHR(9)+CDOW(DATE()) ? [Same day last year: ] ?? olddate(DATE(),-1) ?? CHR(9)+CDOW(olddate(DATE(),-1)) ? [Same day 2 years ago: ] ?? olddate(DATE(),-2) ?? CHR(9)+CDOW(olddate(DATE(),-2)) ? [Same day 3 years ago: ] ?? olddate(DATE(),-3) ?? CHR(9)+CDOW(olddate(DATE(),-3)) ? [Same day 10 years ago: ] ?? olddate(DATE(),-10) ?? [ ]+CDOW(olddate(DATE(),-10)) ? [Yesterday: ]+CHR(9) ?? DATE()-1 ?? CHR(9)+CDOW(DATE()-1) ? [Same day last year: ] ?? olddate(DATE()-1,-1) ?? CHR(9)+CDOW(olddate(DATE()-1,-1)) ? [Same day 2 years ago: ] ?? olddate(DATE()-1,-2) ?? CHR(9)+CDOW(olddate(DATE()-1,-2)) ? [Same day 3 years ago: ] ?? olddate(DATE()-1,-3) ?? CHR(9)+CDOW(olddate(DATE()-1,-3)) ? [Same day 10 years ago: ] ?? olddate(DATE()-1,-10) ?? [ ]+CDOW(olddate(DATE()-1,-10)) ? [Tomorrow: ]+CHR(9) ?? DATE()+1 ?? CHR(9)+CDOW(DATE()+1) ? [Same day last year: ] ?? olddate(DATE()+1,-1) ?? CHR(9)+CDOW(olddate(DATE()+1,-1)) ? [Same day 2 years ago: ] ?? olddate(DATE()+1,-2) ?? CHR(9)+CDOW(olddate(DATE()+1,-2)) ? [Same day 3 years ago: ] ?? olddate(DATE()+1,-3) ?? CHR(9)+CDOW(olddate(DATE()+1,-3)) ? [Same day 10 years ago: ] ?? olddate(DATE()+1,-10) ?? [ ]+CDOW(olddate(DATE()+1,-10))
FUNCTION oldDate(theDate AS Date, offset AS Integer)
- compliments of Ted Roche
- parameters: thedate: date to start from
- offset: number of years offset, positive or negative
- returns: nearest date to the offset that falls on the same day of the week
LOCAL m.theDiff, m.theOffset m.theDiff=DOW(m.theDate)-DOW(GOMONTH(m.theDate, m.offset*12)) m.theOffset=IIF(theDiff>3, 7-m.theDiff, m.theDiff) RETURN GOMONTH(m.theDate, m.offset*12) + m.theOffset
ENDFUNC
--
rk
-----Original Message----- From: ProfoxTech profoxtech-bounces@leafe.com On Behalf Of Gene Wirchenko Sent: Tuesday, May 08, 2018 12:46 PM To: profoxtech@leafe.com Subject: RE: Fun with date calculations in VFP
At 06:27 2018-05-08, Richard Kaye rkaye@invaluable.com wrote:
The latter. And that was the approach I was just working through.
What about the week every few years that you will be disregarding? A year has 52 weeks plus one or two days.[snip]
Sincerely,
Gene Wirchenko
[excessive quoting removed by server]