[Watford] Computers & dates ...

[Alain Williams]

Ho, hum:

----- Forwarded message from RISKS List Owner <risko at csl.sri.com> -----

Date: Sat, 13 Mar 2010 17:40:13 PST
From: RISKS List Owner <risko at csl.sri.com>
Subject: Risks Digest 25.96
To: risks at newcastle.ac.uk

....


Date: Sat, 6 Mar 2010 09:33:46 +0000
From: "Clive D.W. Feather" <clive at davros.org>
Subject: Car insurance bug

I bought a new car a couple of weeks ago, though for obvious reasons [1] I
didn't collect it until Monday.

As soon as I knew the new registration number, I contacted my insurance
company to alter the details. The paperwork finally arrived yesterday. At
one point it reads:

    It has been owned by, and registered to you or your partner,
    for approximately - 1 year(s) 11 month(s).

This puzzled me, so I phoned them, to be told "it always does that for new
cars". Then I realized what had happened; the clue was that the previous
paperwork did *not* have the dash in this text.

The computer must have done something like "now = Feb 2010, bought Mar 2010,
therefore owned for -1 months". Then it converted months to years by
dividing by 12 and determining the remainder. There are two sensible
answers for "-1 div/rem 12" (0 remainder -1 and -1 remainder 11) and which
gets used depends on what properties you want to preserve. Or, in this
case, because nobody had thought about negative inputs!

The only remaining problem: how on earth do I get this information past the
call centre and to the people who actually maintain this code? Perhaps
they read RISKS.

[1] Well, obvious to UK readers - it gives the car a "10" registration
rather than a "59" one, affecting the resale value.

Clive D.W. Feather <clive at davros.org> http://www.davros.org  +44 7973 377646


----- End forwarded message -----

-- 
Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256  http://www.phcomp.co.uk/
Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php
Past chairman of UKUUG: http://www.ukuug.org/
#include <std_disclaimer.h>