Date Manipulation

[joethebow]

I'm using a label printer that's programmed in Basic using MS Hyperterminal, no major problem as I was brought up on BASIC.

My only real problem is the date. I need to print a best before date on the labels.

If I print date$ for today I get 090210

OK using Left$ & right$ I can separate them out and print them as: 10 02 09. so far so good.

I can then convert the strings to numbers using VAL and when I print them I get 10 2 9, still no problem

Now I need to add either 3 14 or 28 days depending on the product labeled. Now you're beginning to see the problem.

Can't have 38 02 09 can we?

So I need a way to add 3 14 or 28 days to the date anmd still have a valad date. I've wrecked my brains for days but haven't come up with a solution that doesn't require a couple hundred lines of code.

Currently I have a fudge in that the PC which drives the labeling machine prints todays date on the screen and asks me for the label's date. It's OK but I need to do all the 3 day products first, then the 14 and finally the 28. I also have to remember to change the date! It works but I'd like something a bit more elegant.

[Mikrondel]

The only real trick is leap years.

This code is more or less what you want. It should be able to handle any number of days. Adjust to taste.

DIM DaysInMonth(1 TO 12) AS INTEGER
DaysInMonth(1) = 31
DaysInMonth(2) = 28
DaysInMonth(3) = 31
DaysInMonth(4) = 30
'... etc. ...



Day = ...
Month = ...
Year = ...

'Leap years
IF (Year MOD 4) = 0 THEN DaysInMonth(2) = 29 ELSE DaysInMonth(2) = 28

Day = Day + 3 'Or any value, really

WHILE Day > DaysInMonth(Month)
   Day = Day - DaysInMonth(Month)
   Month = Month + 1
   IF Month > 12 THEN
         Year = Year + 1
       Month = 1
       'The next line isn't technically necessary if you add less than 59 days
       IF (Year MOD 4) = 0 THEN DaysInMonth(2) = 29 ELSE DaysInMonth(2) = 28
   END IF
WEND

[clippy]

Leap years calculation is wrong! You need to check for century leap years. Every 400 years is a leap year also.

So year MOD 400 = 0 to find those leap years. The other 300 are NEVER leap years!

Will DOS and QB still be around? LOL