@safe pointer value modification

[Jonathan M Davis]

On Saturday, September 8, 2018 11:06:20 AM MDT Neia Neutuladh via 
Digitalmars-d wrote:
> On Saturday, 8 September 2018 at 17:01:33 UTC, Jacob Shtokolov
>
> wrote:
> > So, modification of pointer values is prohibited (if I
> > understand this sentence correctly).
>
> @safe code can't manipulate the pointer itself, in order to avoid
> memory corruption.
>
> So this is forbidden:
>
> void main() @safe
> {
>    int* p = malloc(512);
>    p++;
> }
>
> But in @safe code, the compiler assumes that all pointers you
> receive are valid. And the null pointer is also valid --
> dereferencing it results in a segmentation fault rather than
> memory corruption.

Also, mutating the data that a pointer points to is not mutating the
pointer. So,

*foo = 42;

is not mutating a pointer, whereas

++foo;

would be. So, the first is allowed in @safe code, whereas the second is not.

BTW, if you have questions about D, please ask them in D.Learn. This
newsgroup / mailing list / forum is intended for general discussion on D,
not for answering questions about how the language works.

- Jonathan M Davis