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From: "Jeffrey R. Carter" <spam.jrcarter.not@nospam.acm.org>
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Subject: Re: Newbie Q: How to program in UTC (time/calendar) ?
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reinkor wrote:
> 
> Time1 := Value("1970-01-01 00:00:00",Time_Zone => UTC_Time_Offset);
> 
> gives UTC for the local "input" time "1970-01-01 00:00:00" ?

No, as I understand it, this gives the system time equivalent of 1970-01-01 
00:00:00 in a location where the local time offset is UTC_Time_Offset at that 
time. Note that UTC_Time_Offset is the current offset for the system; it may be 
different from the system's offset at the given time.

> How do I best "input"/enter UTC time (so a reader of the program also
> understand it - an independent of the computer local time)?

If I understand your problem correctly, you only want to input and output UTC
times, and perform basic arithmetic on them. You never want to mix UTC with
local/zoned times.

I'd probably limit myself to the operations in Ada.Calendar. You'll need to
create your own Image and Value operations (PragmARC.Date_Handler may be helpful
for that). The operations in Ada.Calendar (except Clock) are ignorant of time
zones, and so will give you meaningful values.

If you need to mix UTC with time zones then things get more complicated.

The PragmARCs are at

http://pragmada.home.mchsi.com/

-- 
Jeff Carter
"I don't know why I ever come in here. The
flies get the best of everything."
Never Give a Sucker an Even Break
102