1. For datasets crossing the EST/EDT change, split the dataset into
two using sort selecting on date/time, hardcoding that year's date and
time.
2. Write a program that add/ subtracts the specified amount of time.
Open Input / outfile files.
Read input file
Do While not end of file.
If hour >= 4 Subtract 4 (or 4) from hour
Else add 20 to hour
If day > 1 Subtract 1 from day
Else Subtract 1 from month
If month = 1 or 3 or 5 or 7 or 8 or 10 move 31 to day else
If month = 4 or 6 or 9 or 11 move 30 to day else
If month = 2 move 28 (or 29) to day else
If month = 0 move 31 to day move 12 to month subtract 1 from year
Endif endif endif endif endif endif
Write output from input
Read input file
End Do
Close
On Sat, Jun 28, 2014 at 1:53 PM, Hardee, Chuck
<[email protected]> wrote:
> Doesn't help, sorry.
>
> Given all the answers I've had so far, all pointing to things implying
> real-time conversion of timestamps, I think it is clear that I haven't stated
> my need very well.
>
> I have two (currently) sets of data. The data is historical. I have no
> control on how the data is produced, it's from a vendor product which shall
> remain nameless and is irrelevant. In the previous version of the product,
> both sets of data were saved with local times. In the current product, one
> set is saved in UTC, the other in local. The next version will save both sets
> of data in UTC. That being said, I need to be able to convert to and from
> local times and UTC times. And, let me say now, when I say "time", I mean a
> timestamp consisting of yyyy/mm/dd hh:mm:ss.tttttt, that is year, month, day,
> hour, minutes, seconds and microseconds.
>
> I currently have routines to determine the range of Daylight Savings Time, or
> as some of indicated, Summer Time, and other names, all boiling down to the
> same thing.
>
> I have a mechanism to obtain the offset to UTC as a signed value indicating
> before or after UTC, for example. On the East Coast of the US, the UTC offset
> is -5 hours (non-DST) and -4 hours (DST), meaning behind UTC.
>
> The issue becomes when I have a local time that falls outside of the DST
> period but when adjusted for UTC falls within the DST period. Does it get
> adjusted?
>
> For example, given a time of 01:59:59.999999 on the day of the switch to DST,
> when the UTC adjustment is made (assuming my US East Coast example), the time
> would be 06:59.59.999999. Now, the local time was outside the DST range, but
> when adjusted to UTC it falls within the DST range. Does the adjusted UTC
> time get adjusted for DST? And then, having gone thru the narration for local
> to UTC, a similar questions exists for UTC to local, and then similar
> questions regarding the other end of the DST period.
>
> I hope this better explains what I am looking for.
>
> Chuck
>
>
> Charles (Chuck) Hardee
> Senior Systems Engineer/Database Administration
> CCG Information Technology
> Thermo Fisher Scientific
> 300 Industry Drive
> Pittsburgh, PA 15275
> Direct: 724-517-2633
> FAX: 412-490-9230
> [email protected]
>
>
> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:[email protected]] On
> Behalf Of Mike Schwab
> Sent: Saturday, June 28, 2014 12:49 PM
> To: [email protected]
> Subject: Re: Local Time conversion to/from UTC Time
>
> Sometimes it helps to see the whole word in a map.
> http://www.worldtimezone.com/index24.php
>
> On Sat, Jun 28, 2014 at 11:26 AM, Hardee, Chuck
> <[email protected]> wrote:
>> Yes, I have spent a lot of time there going thru the information on the web.
>> I could have easily missed what I was looking for. I will have to go back
>> thru it and read the compressed files with better scrutiny.
>>
>> Charles (Chuck) Hardee
>> Senior Systems Engineer/Database Administration
>> CCG Information Technology
>> Thermo Fisher Scientific
>> 300 Industry Drive
>> Pittsburgh, PA 15275
>> Direct: 724-517-2633
>> FAX: 412-490-9230
>> [email protected]
>>
>>
>> -----Original Message-----
>> From: IBM Mainframe Discussion List [mailto:[email protected]] On
>> Behalf Of John McKown
>> Sent: Friday, June 27, 2014 9:26 PM
>> To: [email protected]
>> Subject: Re: Local Time conversion to/from UTC Time
>>
>> On Fri, Jun 27, 2014 at 5:28 PM, Hardee, Chuck <
>> [email protected]> wrote:
>>
>>> John,
>>>
>>> I am in the process of writing a program that is reading several files.
>>> Some of the files have dates in local and some have dates in UTC.
>>> I want to be able to move between the two time bases as needed.
>>> I don't envision the program reading files from differing time zones at
>>> the same time, but the program could be reading files from any country in
>>> the world.
>>> Currently I'm concentrating on the US so a US based solution would be fine
>>> for the moment.
>>>
>>> Where I can't seem to get my head to go is related to Daylight Savings
>>> Time (DST).
>>> If, for instance, the locale is the east coast of the US, the UTC
>>> adjustment would be -05:00, 05:00 UTC is 00:00 local. If the local time is
>>> 02:00 on the day of the switch in the spring, that's easy, subtract the
>>> signed UTC adjustment from the local time and then add 1 hour. So, 02:00 -
>>> (-05:00) - 01:00 = 06:00 UTC.
>>> But, what if the local time is 01:59? One would subtract the signed UTC
>>> adjustment from the local time and then??? So, 01:59 - (-05:00) = 06:59,
>>> but what about Daylight Savings Time? The current local time being adjusted
>>> is not with the DST range, but the adjusted time via the UTC adjustment
>>> value is. Does DST come into play here? Is the decision based on the local
>>> time or the resulting UTC time?
>>>
>>> A similar question comes into play on the other end of the DST range. If
>>> the local time is prior to the end of the DST range, does one subtract 1
>>> hour from the adjusted time?
>>>
>>> Finally, what about the other direction. If one has a UTC time value, what
>>> are the rules governing the change to a local time with respect to DST?
>>>
>>> I hope my explanation isn't too simplistic. Any thoughts or direction
>>> might have that would help would be greatly appreciated. That also goes to
>>> anyone else that might have some input.
>>>
>>> Thanks,
>>> Chuck
>>>
>>> Charles (Chuck) Hardee
>>> Senior Systems Engineer/Database Administration
>>
>>
>> Have you looked at the IANA TimeZone Database?
>> http://www.iana.org/time-zones Wikipedia entry:
>> http://en.wikipedia.org/wiki/Tz_database
>>
>> That page has a compressed "text" file which contains a lot of TimeZone
>> information. It is public domain. It is what GNU/Linux uses to adjust the
>> local time from the UTC values. It has a _lot_ of data in it. It contains
>> offsets for time zones and dates within that time zone (i.e. such as when
>> the U.S. decided to change when to change to/from DST).
>>
>> Some Perl code at:
>> http://search.cpan.org/dist/Date-Manip/lib/Date/Manip/TZdata.pod
>>
>> Unfortunately, I don't have any example code sitting around. Nor did I find
>> any with a simple Google search.
>>
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>
>
> --
> Mike A Schwab, Springfield IL USA
> Where do Forest Rangers go to get away from it all?
>
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--
Mike A Schwab, Springfield IL USA
Where do Forest Rangers go to get away from it all?
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