Daylight savings time ends Sunday Nov 2

[Stormin Mormon]

Would that make women pushy mother clockers?

[Todd]

:-)

[IGot2P]

25? (360 degrees divided by 15 degrees equals 24)

[Stormin Mormon]

And the time zones span all 57 states.

[Mark Lloyd]

My website has a lot of server-side (PHP) scripts that handle time settings in different places.

In the comments, I call DST "Damn Stupid Time", considering that it makes handling times MUCH more complicated.

For one thing, without DST every day would be 24 hours long.

[Mark Lloyd]

[snip]

It's 25 rather than 24 because the 0-degree line is in the MIDDLE of a time zone. So, on the other side of the world there are 2 half-width zones, -12 hours and +12 hours which are 24 hours apart (NOT the same time).

[Scott Lurndal]

I would think one would use UTC and simply convert upon display for the correct TZ rather than farting around with DST conversions. Microsoft's insistance on storing time relative to the local timezone was a poor choice, that's true.

[Mark Lloyd]

[snip]

My server runs on Red Hat Linux, and storing time as UTC (no DST!) does help a lot. However, there are still numerous situations requiring display of local time, and INPUT of local time.

[Scott Lurndal]

Things that strftime(3)/strptime(3) won't handle?

[Todd]

Hi Mark,

1+

So do mine. Never had any trouble what-so-ever.

Do you remember when Windows would keep resetting 2:00 back to 1:00 over and over. Told everyone to leave there computer off that night. Chuckle, Chuckle.

Heads up on Red Hat 7. It is pure 64 bit. If you are running any 32 bit Windows apps under Wine, y o u a r e s o s c r e w e d. It is an absolute disaster.

-T

[Mark Lloyd]

[snip]

Yes.

Also, there's a way to set Windows to use a clock chip using UTC.

And I need the 64-bit clock, since I need times after early 2038.

[Mark Lloyd]

[snip]

These help a lot. There's still a lot they don't do.

For one thing, they depend on having the correct timezone set. This requires reading the PHP database. One of the main reasons is to help a user select a timezone (I display this info at

One thing I want to do is determine the amount of time between now and some future event.

Subtracting the current time from the future time returns the correct number of seconds, but I want it in days. I can divide this number by

86400 (the number of seconds in 24 hours). This is SOMETIMES right.

The first thing I did was calculate the days until Thanksgiving. The result for today is correct. When I did it on Halloween, the result was

1 hour off. The cause of this mess is (of course) DST. One day (this year in the US it was Nov 2) has 25 hours it in. Another day in the Spring will have 23 hours (the number of hours per day can be found by subtracting 00:00:00 today from 00:00:00 tomorrow and dividing by 3600).

So I need to correct for that. If the current DST state is different from the future DST state, the time will need to be adjusted by the DST offset.

DST offset is usually 0 (no DST) or 3600 (1 hour), although there can be exceptions. Currently the only exception seems to be 1800 for Lord Howe Island.