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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Trivial question: how to avoid confusing sec, min, hour and day
 in a program?
Date: Sun, 5 Sep 2021 15:42:49 +0300
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On 2021-09-05 10:27, Dmitry A. Kazakov wrote:
> On 2021-09-05 08:56, reinert wrote:
>> Anybody with good ideas on how (in a simplest possible way) to avoid 
>> to confuse between representation of time as seconds, minutes, hours 
>> and days in an Ada program?
> 
> Just use the standard type Duration.


But note that:

- Duration is a fixed-point type, not floating point, so it has a fixed 
resolution, Duration'Small.

- The resolution and range of Duration are implementation-defined, and 
the standard does not guarantee much. RM 9.6(27) says:

"The implementation of the type Duration shall allow representation of 
time intervals (both positive and negative) up to at least 86400 seconds 
(one day); Duration'Small shall not be greater than twenty milliseconds."

(Aside: I wonder why this paragraph is not in RM A.1, "The Package 
Standard", where the Duration type is introduced.)

If you want your code to be portable, define your own type for "time in 
seconds", choosing the properties your application needs.

That said, I believe that GNAT versions typically provide a 64-bit 
Duration type that has enough precision and range for most applications 
dealing with times on human scales. But perhaps not on nuclear, 
geological or astrophysical scales.