Question

Let’s say you have a “void *a” and “void *ptr” that point to different addresses defined in your code. Then I was wondering if these two lines were equivalent and functionally the same?

    *((unsigned **)((char*)ptr+4)) = a;

and

    *((unsigned *)((char*)ptr+4)) = a;

The second one throws a warning that “assignment makes integer from pointer without a cast”

Also, would it also be the same as the above to just do?:

    *((char*)ptr+4) = a;

Answer 1

These are not equivalent. #1 resolves (char*)ptr+4 to be a pointer to unsigned (*unsigned), while #2 resolves it to be unsigned.

a is a void pointer, so it can be casted to *unsigned, but not to unsigned (implicitly), that’s why you get the warning.

The #3 resolves the same to a char, which would also yield a warning.