Does a day start at 1:00 AM everwhere?
kray at sonsothunder.com
Fri Oct 27 10:49:58 EDT 2006
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 this
> 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 not
> 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 April).
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-entered
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 space
convert tUserDate to seconds
convert tFileDate to seconds
if tUserDate = tFileDate then
answer "Same day"
answer "Different day"
Will this work for you?
Sons of Thunder Software, Inc.
Web site: http://www.sonsothunder.com/
Email: kray at sonsothunder.com
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