I thought this was easy! Well I discovered a bug in some old code and now I
am pulling my hair out trying to fix / code this... an interesting puzzle
for those of you so inclined on a Sunday :)
The Task
The function needs to add a variable number of months to a given date:
function date_AddMonth monthNum, startDate
....
end date_AddMonth
Seems easy no?
Use Case
I have some bank statements with statement numbers issued each calendar
month. First statement is numbered 01 and is for October 2002. I want to
work out what the month and year is for the nth statement.
First Try
function date_AddMonth monthNum, startDate
convert startDate to dateItems
put startDate into someDate
put item 2 of someDate into oMonthNum
put oMonthNum + monthNum into overMonthNum
put overMonthNum into item 2 of someDate
convert someDate to dateItems
return someDate
end date_AddMonth
I thought this worked fine, but if the startdate is lets say January 31 -
well adding a month basically goes to Feb 31st which converts to March... so
you need to do something else.... but what??? Been trying a few hours now
and things have got complicated involving for a start working out leap
years!
Unit Test
Well if anyone can figure this out - here is the test to pass:
on mouseUp
-- put "Friday, January 31, 2002" into abbeyStartDate
put "2002,1,31,1,0,0,5" into abbeyStartDate
put 1 into lastMonth
repeat with statementNumber = 1 to 100
put item 2 of date_AddMonth(statementNumber, abbeyStartDate) into
someMonth
put someMonth
if statementNumber mod 12 is not (someMonth - 1) then
put merge("Failed adding [[statementNumber]] to [[abbeyStartDate]].
Resulted in [[someMonth]]")
answer "Failed!"
exit to top
end if
end repeat
answer "Success!!"
end mouseUp
I cant figure it out???
More Problems
Sometimes when you dig things just get more complex. While debugging i am
finding that sometime adding numbers to the 2nd item of the dateitems and
then reconverting to dateitems works fine, and then mysteriously at others
it does not... seemingly getting confused by having the wrong daynum in item
7... still not figured what is going on...
Stuff that may help?
Here is a function you may need (well thats the direction I am trying):
function date_MaxDaysInMonth someDate
/*
Base on the rhyme:
30 dyays has September, April, June and Novemeber
All the rest have 31
Except Februaruy
Which has 28 and 29 on a leap year
*/
convert someDate to dateItems
put item 2 of someDate into monthNum
return date_MaxDaysInMonthNum(monthNum)
end date_MaxDaysInMonth
function date_MaxDaysInMonthNum monthNum
/*
Base on the rhyme:
30 days has September, April, June and Novemeber
All the rest have 31
Except Februaruy
Which has 28 and 29 on a leap year
*/
put 30 into item 9 of maxDaylist
put 30 into item 4 of maxDaylist
put 30 into item 6 of maxDaylist
put 30 into item 11 of maxDaylist
put 31 into item 1 of maxDaylist
put 31 into item 3 of maxDaylist
put 31 into item 5 of maxDaylist
put 31 into item 7 of maxDaylist
put 31 into item 8 of maxDaylist
put 31 into item 10 of maxDaylist
put 31 into item 12 of maxDaylist
if date_IsLeapYear(someDate) then
put 29 into item 2 of maxDaylist
else
put 28 into item 2 of maxDaylist
end if
return item monthNum of maxDaylist
end date_MaxDaysInMonthNum
function date_IsLeapYear someDate
convert someDate to dateitems
put 2 into item 2 of someDate
put 29 into item 3 of someDate
convert someDate to dateitems
return item 2 of someDate = 2
end date_IsLeapYear
- but maybe someone already has a simple function that passes this test?
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