A challenge: adding months to a date?

[Björnke von Gierke]

I like challenges :)
The following function adds monthNums months, and gives you the last 
day of that month, if the original day number was more then the target 
month actually has days. Works on 2.8 (does NOT work correctly for 
2.8.1 rc3 due to bug 4915)

function date_AddMonth monthNum, startDate
   convert startDate to dateItems --does not work if startDate is a 
system date
   put item 3 of startDate into theDay
   put 1 into item 3 of startDate
   add monthNum to item 2 of startDate
   convert startDate from dateItems to dateItems
   put item 2 of startDate into theMonth
   put item 1 of startDate into theYear
   put getMaxDays(theMonth, theYear) into maxDay
   if theDay > maxDay then
     put maxDay into theDay
   end if
   put theDay into item 3 of startDate
   --convert startDate from dateItems to <favorite date format>
   return startDate
end date_AddMonth

function getMaxDays theMonth, theYear
   put "1,January,3,March,5,May,7,July,8,August,10,October,12,December" 
into Months31
   put "4,April,6,June,9,September,11,November" into Months30
   if theMonth is among the items of Months31 then
     put 31 into HowManyDays
   else if theMonth is among the items of Months30 then
     put 30 into HowManyDays
   else --February
     if (theYear mod 400 = 0) or (theYear mod 100 <> 0) and (theYear mod 
4 = 0) then
       put 29 into HowManyDays -- leap year
     else
       put 28 into HowManyDays
     end if
   end if
   return HowManyDays
end getMaxDays


-- 

official ChatRev page:
http://chatrev.bjoernke.com

Chat with other RunRev developers:
go stack URL "http://homepage.mac.com/bvg/chatrev1.3.rev"