supportlink (Week no. calculation)

[Steve Huckvale]

Hi again Johan,

For what it's worth, here's the section of QUIZ code I wrote recently.
I'm sure there will be more elegant methods available to you though;

; --------------------------------------------------------------------
;
; *** ASSUMPTIONS ***
;
;   Week 01 is the first *complete* week of a year, e.g. if the
;   4th of Jan 1999 is a Monday, then 1-3 Jan are week 52/1998
;
;   Monday is considered the first day of a given week, Sunday
;   is the last.
;


Def TEMPDAY = Mod(Days(DUEDATE),7)
Def DAYofWEEK = TEMPDAY - 1 if TEMPDAY > 0 else 6

;DAYofWEEK is the day of the week when DUEDATE falls (0=MON, 6=SUN)

Def ASC0101 char*8 = ascii(DUEDATE)[1:4] + "0101"
Def DATE0101 date = date(0,nconv(asc0101))

;DATE0101 holds the 01/01/YYYY - where YYYY is year in which DUEDATE falls

Def PREVMONDAY Date Format DDMMYY = &
  Date(Days(DUEDATE)-(DAYofWEEK))

;PREVMONDAY is the Monday of the week in which DUEDATE falls.

Def OFFSET = Mod((Days(PREVMONDAY) - Days(DATE0101)),7)
Def FIRSTMONDAY Date Format DDMMYY = Date(Days(DATE0101) + OFFSET)

;FIRSTMONDAY is the first Monday of the calendar year in which DUEDATE
falls.

Def WEEKNUM Char*2 = &
  "52" if PREVMONDAY < DATE0101 &
  else Ascii((((days(PREVMONDAY)-days(FIRSTMONDAY)) / 7) + 1),2)
Def WEEKNOYEAR Char*7 = WEEKNUM + "/" + Ascii(FIRSTMONDAY)[1:4]
;
; --------------------------------------------------------------------

DUEDATE and WEEKNOYEAR are the key here, the latter being 7 chars for
display in the format ww/yyyy, representing the Week number in which
DUEDATE falls.

Steve Huckvale
Analyst Programmer
Cosworth Racing Limited

********************************************
* Any views or opinions stated above are my*
* own and should not be taken or implied to*
* represent those of my employer.          *
********************************************
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