The extra week in 2000 - over at de Jager's. Another way for data/apps to crap out.

greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread

http://www.year2000.com/y2kcurrent1.html

"It turns out that a 54-week year happens once every 28 years, so the last time was 1972 ... well before the birth of many software packages now in common use.

"This wouldn't be a problem if programmers had been aware of it, but we've seen a number of programs that assume that the number of weeks in a year is always 53. This can cause two kinds of problems:......"

-- lisa (lisa@work.now), December 16, 1999

Answers

Gee, and I thought there were only 52 weeks in a year. I think we should call NASA for confirmation.....

-- bb (b@b.b), December 16, 1999.

54 Weeks in 2000: Another Y2K Problem!

by Stan Sieler (sieler@allegro.com) Michael Hensley (michaelh@allegro.com) Barry Lake (barry@allegro.com) Allegro Consultants, Inc. (http://www.allegro.com)

Many software applications define a week-of-year, which is used for a variety of purposes. Usually, such weeks are defined as starting on Sunday and ending on Saturday. (These week-of-years are sometimes called "fiscal week" or "calendar week.")

A normal year has 53 weeks, where 51 or 52 are "complete" weeks, and 2 or 1 are "incomplete" (because they start or finish in the prior or following year).

For example, 1999 has 53 weeks. The first week has two days in 1999 (Friday, January 1 and Saturday, January 2). The last week has only one day in 1999 (Sunday, December 31).

If there were only 364 days in a year, and if the year started on a Sunday, then it would have exactly 52 weeks. However, we aren't that lucky, and no year ever has fewer than 53 weeks.

The year 2000, as fate would have it, has 54 weeks! The first week has one day in 2000 (Saturday, January 1), and the 54th week has one day (Sunday, December 31).

It turns out that a 54-week year happens once every 28 years, so the last time was 1972 ... well before the birth of many software packages now in common use.

This wouldn't be a problem if programmers had been aware of it, but we've seen a number of programs that assume that the number of weeks in a year is always 53. This can cause two kinds of problems:

invalid restrictions on data entry; We have seen code that checks user-entered week numbers, incorrectly restricting them to the range 1..53. These programs would prevent the user from entering a week number of 54.

run time aborts If the code is written in range-checking language (e.g., Pascal), or if it uses the week number as an index into an array of 53 elements, the program could abort, or (even worse) possibly pickup incorrect information and continue running.

This isn't just a theoretical problem, of course ... we encountered it in code we started to maintain for one of our customers. The team that foundand characterized this problem was Barry Lake and Michael Hensley.

-- Powder (Powder@keg.com), December 16, 1999.


Accountants just can't get a break with this CDC stuff........

-- lisa (lisa@work.now), December 16, 1999.

"For example, 1999 has 53 weeks. The first week has two days in 1999 (Friday, January 1 and Saturday, January 2). The last week has only one day in 1999 (Sunday, December 31)."
Whoever wrote this article used a non-Y2K compliant calendar that says 1 Jan 2000 is Monday, thus making 31 Dec 1999 a Sunday since 31 Dec 1999 is a Friday on my Y2K compliant calendar.
And people still think it's going to be a BITR?

-- just wondering (what.it.is@about.com), December 16, 1999.

Just Wondering...

Huh? I've read the article a couple of times and still don't see where they say Jan 1, 2000 is a Monday... are we reading the same article?

-- C (c@c.com), December 16, 1999.



Ya know, just wondering, I didn't even catch that.............

-- lisa (lisa@work.now), December 16, 1999.

C
They actually said that 31 Dec 1999 was a Sunday. This could only happen if they were looking at a non-Y2K compliant calendar that has 1 Jan 2000 as a Monday.

The reason I made the statement is that a simple test to see if your VCR or other home appliance that displays dates and days of the week is Y2K compliant or not is to set the clock to 11:59 on 31 Dec 1999, let it roll over to 1 Jan 2000 and see what day of the week the appliance thinks it is. If it says Monday, it's non-Y2K compliant. If it says Saturday, it's Y2KOK.

-- just wondering (what.it.is@about.com), December 16, 1999.

Rule of thumb: NEVER hardcode in the number of weeks!

-- Mad Monk (madmonk@hawaiian.net), December 17, 1999.

wow...Wow...WOw...WOW!

( And I almost never say WOW! )

-- GoldReal (GoldReal@aol.com), December 17, 1999.


Speaking of hard-coding........ everybody (you IT people) remember those 'little' things that need to be adjusted 12/31?

-- lisa (lisa@work.now), December 17, 1999.


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