Pointers - Is it safe to point to invalid memory?

[Richard (Rikki) Andrew Cattermole]

On 17/08/2025 11:21 AM, Ali Çehreli wrote:
> On 8/16/25 8:44 AM, Brother Bill wrote:
> 
>  > Source: Programming in D book, page 432, chapter 68.8
>  > Quote: It is valid to point at the imaginary element one past the end of
>  > an array.
> 
> I am the author. I have no problem with that part of the book: The quote 
> is correct.
> 
> Both C and C++ explicitly state what I wrote above. That guarantee is 
> necessary so that looping over the elements of an array does not make 
> the program illegal just because the array may be sitting at the end of 
> an allocated page.
> 
> D does not reject that part of C's memory model.
> 
> Ali

We in fact do reject it.

"When a pointer to T is dereferenced, it must either have a null value, 
or point to a valid instance of type T."

"Undefined Behavior: dereferencing a pointer that is not null and does 
not point to a valid instance of type T."

https://dlang.org/spec/type.html#pointers