Re: Two questions on arrays with size defined by variables

On 09.02.2025 18:29, Andrey Tarasevich wrote:

On Sun 2/9/2025 9:19 AM, Janis Papanagnou wrote:

>
I had other languages in mind.[*]
>
Janis
>
[*] For example Simula:
>
begin
     integer n;
     n := inint;
     begin
         integer array arr (1:n);
         arr(5) := 9;
     end
end
>
(Which is also understandable, since in Simula declarations must appear
before statements in any block.)

 
 
Well, in that case your previous mentions of "block context" are not
related to VLAs at all. You apparently meant that in order to introduce
a new declaration, any new declaration "in the middle of the code" one
needs to open a new block - just because the language requires all
declarations to reside at the beginning of a block.

Yes, but that (declaration-statement-ordering) is language dependent;
in Simula it's [for this reason] a necessity, but not necessarily in
other languages. - Whether any language allows that or not is not a
given per se. - I just did not know how "C" handles VLA declarations;
and that's why I tried it whether it works or not. But a positive
outcome of my tries is still no proof; my test-wise - deliberately
wrong! - assignment to 'a[99]' produced also no compiler complaints,
so I want to get an affirmation whether you need an extra scope.
The sample from the Net that had the array size parameter passed as
function argument also didn't answer that.

 
This was the case in C90, where we also sometimes had to open new blocks
to introduce new declarations. But starting from C99 this is no longer
necessary. In C99 one can simply place declarations in the middle of the
code "C++-style" (the underlying semantics is still different from C++,
but syntactically/superficially it looks pretty much the same).

Janis