Does a day start at 1:00 AM everwhere?
mpetrides at earthlink.net
Fri Oct 27 10:20:41 CDT 2006
While we are on the topic of dates, I've been thinking about creating
a "countdown" calendar, clocking the number of days remaining between
today's date and some future date (March 31, 20010 specifically).
Any tips on how I can do this? Do I have to convert dates into
seconds in order to subtract one from the other? Thanks.
On Oct 27, 2006, at 9:49 AM, Ken Ray wrote:
> On 10/27/06 7:52 AM, "Mark Powell" <mark_powell at symantec.com> wrote:
>> I have a user-specified date. I want to convert it to seconds and
>> factor in 86400 to establish the range of seconds for that date,
>> so that
>> I can compare a file's creation date to determine whether that
>> file was
>> created on that specified day. The problem is I am not sure what is
>> used as the starting point for a date's seconds counter. At 6:42
>> morning, I ran this:
>> put the short date into theDate
>> convert theDate to seconds
>> put ((the seconds - theDate) / 3600)
>> and got 4.710556, which suggests that a date starts at 1:00 AM and
>> midnight. Is this accurate? And more importantly, is this the
>> way the
>> computation would be handled on any client machine anywhere?
> Welcome to the wonderful world of dates in Revolution!
> Seriously - Many of us have struggled with date arithmetic in Rev
> as it
> relates to other parts of the world. The short answer is "no", it
> is not
> always 1:00 AM everywhere when you convert a date to seconds and
> back again.
> In fact for me, I get 2:00 AM.
> Date conversions give you different results depending on a number of
> factors: is Daylight Saving Time (DST) or Summer Hours currently being
> observed? What hemisphere are you on? Are you looking at a date
> that is
> "across" a DST boundary (such as the current date being in March
> and you're
> looking at a date in May, which is across the DST "boundary" in
> I wish it were easier, but it's not... in your *specific* application,
> though, if you're just trying to compare one date to another, you
> can strip
> off the time from the file creation date, and then convert the user-
> date and the date from the file creation to seconds and compare - they
> should be the same:
> put fld "UserDate" into tUserDate
> put fld "FileCreationDateTime" into tFileDateTime
> put word 1 of tFileDateTime into tFileDate
> -- assumes a datetime where the date and time are separate by a
> convert tUserDate to seconds
> convert tFileDate to seconds
> if tUserDate = tFileDate then
> answer "Same day"
> answer "Different day"
> end if
> Will this work for you?
> Ken Ray
> Sons of Thunder Software, Inc.
> Web site: http://www.sonsothunder.com/
> Email: kray at sonsothunder.com
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