In comp.lang.fortran Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
[...]
>
> An unsigned time_t makes it impossible to represent times before 1970.
> Not all software is going to care about that, but in my opinion it's
> an unacceptable price.
>

I read somewhere that the reason for a signed time_t was mainly that
this type was nor just used for time stamps, but also for time
differences.

--
Klaus Wacker klaus.w.wacker@t-online.de
51°29'7"N 7°25'7"E

David Brown <david.brown@hesbynett.no> schrieb:
> On 13/11/2022 03:00, Keith Thompson wrote:

>> But since C and C++ require support for 64-bit integers anyway, it
>> should be practical to require 64-bit time_t even on 32-bit systems.
>
> Yes.
>
>> (Not sure about Fortran.)
>
> (That's better than me - I haven't a clue about Fortran!)

Fortran has the DATE_AND_TIME inrinsic, which returns the the date
and time in calendar format, either as YYYYMMDD and HHMMSS.SSS and
[+/-] HHMM for the zoneif you chose character arguments, or as an
array of integer with the same info.

The library is supposed to take care of how to get the value
from the operating system, user programs need not bother.

There are also non-standard extensions which mimic system
behavior, but those should be avoided, at least in new code.

On 11/14/2022 3:54 AM, gah4 wrote:
> On Monday, November 14, 2022 at 1:09:40 AM UTC-8, David Brown wrote:
>
> (snip)
>
>> Small embedded systems which also track the date will generally not do
>> so using Unix epoch timestamps - it's a lot easier to hold a structure
>> with second, minute, hour, day, month, year fields and update it. That
>> avoids all the mess of locales and time and date conversions.
>
> Reminds me that I have a sprinkler timer that you program with the year.
> It needs the year because you can set it to water on even or odd days,
> and so has to get leap years right.
>
> But if it watered on the wrong day, it wouldn't be the worst thing.

Unless code enforcement catches you watering on the wrong day ... :(

>
> You can program it by week days, then it doesn't even need the month,
> but you still have to set year and month.