Question

Let’s say you start with a void pointer, or a char pointer, or an int pointer, or whatever you would like to name.

    void *p = // initialized to something here

And we do a conversion like

    *((int *)((char *)p + 6)) = 5;

Does this mean we are basically casting a void pointer to a char pointer, doing some arithmetic, casting that to an int pointer, and then de-referencing it to store 5?

Or do we need to cast the char pointer back to a void pointer before it is safe to cast it to the int pointer?

* Also, before casting from char* to int*, does there need to be a de-reference somewhere before the conversion?

Answer 1

The conversion you have shown is syntactically valid C. Casting through a void * type on the way to int * makes no difference.

Whether it is semantically correct depends on whether the memory pointed to by (char *)p + 6 is correctly sized and aligned for access as int.