Re: Examining individual bytes of an integer

["Randy Brukardt" <randy@rrsoftware.com>]

"Niklas Holsti" <niklas.holsti@tidorum.invalid> wrote in message 
news:g2k5fbF9thnU1@mid.individual.net...
> On 18-10-15 13:18 , AdaMagica wrote:
>> Am Sonntag, 14. Oktober 2018 23:28:57 UTC+2 schrieb Niklas Holsti:
>>> Not guaranteed, but implied by the "Implementation advice":
>>>
>>> - RM 13.3(11): X'address denotes the address of the first of the
>>> storage elements allocated to X.
>>>
>>> - RM 13.3(14): For an array X, X'Address should point at the first
>>>  component of the array [...].
>>>
>>> Combining those two, it seems that the first element of an array
>>> should start at the first storage element (= lowest address)
>>> allocated to the array.
>>>
>>> By reasonable induction  :-)  the second, third, etc. array
>>> elements follow in increasing address order. But not _guaranteed_,
>>> I agree.
>>
>> There is the old Dewar rule that no compiler is doing nonsense. It
>> would be a very unfriendly compiler to not follow this advice.
>
> As I remember it, Dewar's rule says that the Ada *RM* does not specify 
> nonsense, meaning that if some reading of the RM seems to be nonsense, it 
> is the wrong reading.

That's correct.

> I don't remember Dewar saying anything similar about compilers.

Me either. Compilers do nonsense all of the time (usually not on purpose, 
though).

                           Randy.