On Jan 12, 2006, at 7:53 AM, Aleksandar Donev wrote:
> Bertrand Meltz wrote:
>
>> In the example below, is typ%in a whole array, in which case its
>> bounds should be (0,4), or an array section, in which case its bounds
>> should be (1,5).
> It is an array section.
I always have to look this stuff up, because otherwise I get the fine
points of distinction wrong.
I agree that this is a section, by Aleksander's derivation, but... the
original question has a misconception in implying that "whole array" or
section are the only two possibilities. If you look at the definition
of LBOUND, you won't find the word "section". Instead, you will find
"If ARRAY is a whole array or array structure component..". So let's
look at that question instead of the question of whether ARRAY is a
section, which doesn't seem to have much to do with the definition of
LBOUND.
Looks to me like, although typ%in is a section (per Aleksander's
derivation), it is also a structure component. Odd, I thought those
were mutually exclusive, but it sure doesn't look like it to me. The
definition of structure component (R614) is pretty simple. It is just a
data-ref (all these kinds of things are that) with the constraint that
there shall be more than one part-ref (typ%in has 2) and that the
rightmost part-ref shall be of the form part-name (which "in" is).
In fact, the standard has a similar example in Note 6.5, where it gives
array_parent(1:n)%scalar_field as an example of a structure component.
Thus, the bounds should be (0,4).
> The only time something with % in it is not an array section is when
> the
> last piece is a whole array:
Other matters aside, a "whole array" is never a "piece" of any other
syntax. As noted above, a whole array is defined to be a named array.
That means just a plain, unadorned name. That does not mean a component
name because a component name alone does not identify array. You can't
just talk about the array "in" without qualifying that you mean typ%in.
>> Some compilers even
>> interpret typ%in and pt_1 differently, which adds to my confusion.
That's pretty definite. Even if Aleksander and/or myself are messed up
somewhere on the section/component/whole-array question, the bounds
resulting from pointer assignment are defined in terms of lbound. So
whatever lbound gives for typ%in had better be the lower bound that
pt_1 gets (and thus that lbound returns for it).
--
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| -- Mark Twain
