A tiny New Year's programming challenge

[Dieter]

(01-03-2015 01:24 PM)Gilles Wrote:  I first tried to handle all the exceptions (negative result etc.) but it looks like marmalade ! So I change to handle all the cases in a single way. The general idea is :
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[ snip general idea ]
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Interesting approach.
Just for comparison, I did it this way:

• Since 4 January is always in week 01, simply determine its weekday (Mon=0 ... Sun=6) and count back this number of days. This is the start of the year's first week.
• Determine the difference between this day and the entered date.
• If the result is < 0
        add 7 days to get the day number. The week is the last of the previous year, i.e. 52 or 53.
  else
       divide by 7 and use the integer part and the remainder (both +1) to get week and day number.
       If this result is week 53
            check if it exists
            If it doesn't
                 return week 1 of the next year.
  

My 34s program includes a short subroutine that returns the last week# for a given year.

By the way:

(01-03-2015 01:24 PM)Gilles Wrote:  - Interger division by 7 (IDIV2 returns integer parts and remainder)

Yes, that's a very handy and useful command. Some time ago I suggested such a command that returns both the integer part and the remainder for the 34s (like DIV in x86 assembly language), but it did not make it into the final firmware. ;-\

(01-03-2015 01:24 PM)Gilles Wrote:  Note that there is nothing special to handle dd.mmaaaa or mm.ddaaaa format. The 50G manage this (DATE+ DDAYS TSTR) and by chance (?) 1.012015 means the same thing in the 2 formats (first january)

Yes, I used this trick as well. ;-) On the other hand the 34s has a special DATE→ command that assembles year, month and day (given individually) into dd.mmyyyy or mm.ddyyyy or yyyy.mmdd, depending on the current date mode setting.

Dieter