On Sat, Aug 16, 2025 at 10:28:15PM +0000, Andy Valencia via Digitalmars-d-learn
wrote:
> On Saturday, 16 August 2025 at 21:58:30 UTC, Paul Backus wrote:
> > Creating a pointer that points out-of-bounds does not, by itself,
> > result in undefined behavior.
> >
> > However, such a pointer would not be considered a [safe value][1],
> > because dereferencing it *would* result in undefined behavior.
>
> I'm just pondering whether the intention was to accomodate this
> looping pattern:
>
> ```d
> int sum_values(int* p, uint nval) {
> int result = 0;
> foreach(_; 0 .. nval) {
> result += *p++;
> }
> return result;
> }
> ```
>
> A C idiom (I've so very much embraced not using pointers in my D
> world) which technically leaves "p" pointing beyond the memory range.
> Perhaps this is the special case being addressed?
[...]
Why does it need to be addressed? D has arrays and slices that know
their own length. From p and nval you can form the slice p[0 .. nval]
which lets you iterate safely without risking illegal memory accesses:
int sum_values(int[] arr) {
int result = 0;
foreach (i; arr) {
result = i;
}
return result;
}
T
--
Never wrestle a pig. You both get covered in mud, and the pig likes it.
