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Leap Day Problems

Novell Cool Solutions: Trench

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Posted: 8 Mar 2000

The rule laid down by Pope Gregory XIII in 1582 is that leap years are those that are divisible by four. Apparently he had sufficient chutzpah to make dictates like that and have everyone abide by them. (It's commonly thought that he blazed the trail for Bill Gates.) Why we even care about Pope Gregory, aside from our fondness for the Gregorian chant, is simple. His seemingly inocuous pronouncement that the Century years are only leap years if they are also divisible by 400 has screwed things up for some of us. This is what can happen when you stray away from simple math and start with the arbitrary conditions.

For example, the year 2000 is divisible by 400, but 1900 was not, even though it is divisible by four. If the computer thinks it is dealing with the year 1900, not 2000, it will have a problem because 2000 is a leap year, but 1900 was not. Therefore, all entries for February 29, 1900, could theoretically be rejected.

Well, it didn't bring the world to its knees, but it turns out lots of system administrators were surprised by the effects of the Leap Year Bug, which ended up biting in a few amusing ways. Here's what happened to some of our Cool Readers:

Bob M., USA, wrote:

I did have a leap day problem. I hadn't had any problems with Y2K so I had dismissed leap day as so much hype.

I'm a network administrator for a medium size school district. We have an older DOS application called "Accelerated Reader." The librarians in the early elementary buildings really like this program as it encourages their students to read - always a good thing.

On 2/29/00 I got a rather frantic phone call from my favorite(?) librarian (if you know anything about school librarians...) that her students couldn't access the program. She asked if I could change the date on the server to 3/1 so her students could run the program. After dismissing that idea rather quickly, I instructed her on how to change the dates on the Win95 & Win3.x machines.

This glitch hardly caused the end of the world as we know it to cease, but was rather a minor irritant. (Actually any call from my favorite librarian is a major irritant!)

Eric B., Denmark, wrote:

So far the only y2k bite I have noticed was with my watch, a Timex Triathlon which didn't realize this year was a leap year.

Maybe some of the household electronics have similar problems, but I haven't noticed yet.

Mary H. wrote:

My accounting system (specific to the legal market) has a utility to clear out uncommitted transactions, i.e. someone aborted the process on the client. Well, it was actually not Y2K compliant so it reset the error date to Feb 29, 1910. But since there was no Feb 29, 1910 it get incrementing the days and retrying to fix this transaction - doing this filled up my 2MB transaction log in short order and I had to dump and init it. No fun because we've been having an ongoing problem in another area and had finally just gotten the system up an hour before this happened. Double ouch!

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