Re: utime() and GMT

From:

David Lowndes <DavidL@example.invalid>

Newsgroups:

microsoft.public.vc.language

Date:

Wed, 28 Oct 2009 20:39:25 +0000

Message-ID:

<7d9he5pi7o6hjftio5tmabusrktqai0fa8@4ax.com>

I start with the time in "seconds since midnight, Jan 1st 1970" format
(time_t) - I don't think there is any simple way to convert to/from
FILETIME.

You can do it, but it may take a couple of hops. The COleDateTime
class may wrap enough of this functionality to make it look simple.
However...

And there's still the issue of avoiding nasty outcomes at the moment
that the timezone changes.
Filesystems are always in UTC - seems annoying that I can't just read/
write the time directly in UTC without the complication of the local
time zone getting in the way

The way it normally works is this:

A user (normally) likes to work in their local time.
The internals work in UTC.

.... so wherever there's a transition between the 2 you perform the
appropriate local/utc conversion.

If the user has entered the time initially, convert it to UTC then
save it. When reading back to present to the user you go from UTC to
local.

Have a look at the MSDN knowledge base article 932955 "How to handle
dates and times that include DST" - that seems to explain the
situation.

Dave