On Jan 31, 2008, at 2:33 PM, Sarah Reichelt wrote:
On Feb 1, 2008 6:52 AM, Devin Asay <[EMAIL PROTECTED]> wrote:
I am working on a scheduling program that includes the ability to
schedule an event every other week over a specific time period. To
determine whether the event should occur during any given week during
the time period I do some simple date math to figure out whether a
multiple of 14 days have passed since the first occurrence of the
event. Let's say I've scheduled an event for every other week on
Friday, beginning January 11, 2008 and ending April 11, 2008. For any
given week on my calendar I can calculate whether the event should
show up using this algorithm (pseudocode):
get the date of the first occurrence of the event and convert it to
seconds
get the date of that the event should fall on if this week falls in
the every-other-week pattern, convert it to seconds
subtract date 2 from date 1
divide the difference by (60*60*24*14) --the number of seconds in 14
days
if the difference divides evenly (modulo division = 0) then the event
should occur in the week in question
This works fine for a few weeks, but then inexplicably fails. For
example, Jan. 11, Jan. 25, Feb. 8, Feb. 22, and March 7 all show the
event properly. But anything after that fails; i.e., March 21,
April 4.
I would assume that daylight savings changes for you between March 7 &
March 21, so that explains the hours difference.
AAAARRRGH! Of course, I'd completely forgotten that the daylight
savings time change was moved up to March! At first I was wondering
if it had something to do with the leap year, but that wouldn't have
explained why March 7th was okay.
Thanks Stephen, Sarah, Jacque and Colin for your responses and
suggestions. I can fix it now.
I love this list!
Devin
Devin Asay
Humanities Technology and Research Support Center
Brigham Young University
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