Any functional difference between (*p)->some_var and *p->some_var

Question

I have seen several C code examples which utilise the (*p)->some_var way of working with pointers (using parens around the pointer).

My question is, is there any functional difference between the two methods of working with C pointers, and if so, how did this difference come about?

Answer 1

Those do not do the same thing at all. Compare:

(*p)->some_var // aka (*(*p)).some_var

This means "p is a pointer, which we dereference, then dereference again to access a field."

*p->some_var // aka *((*p).some_var)

This means "p is a pointer, which we dereference to access a field, which is a pointer which we dereference."