Does a day start at 1:00 AM everwhere?

Marian Petrides mpetrides at earthlink.net
Fri Oct 27 10:34:26 CDT 2006


make that 2010  not 20010 :-)
On Oct 27, 2006, at 10:20 AM, Marian Petrides wrote:

> 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  
>>> 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"
>>   else
>>     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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