Question

int * const const * b

What does it mean? cdecl says declare b as pointer to const const pointer to int.
Can someone explain it?

Answer 1

const const is redundant, it will reduce to const.

So let’s rewrite that:

int * const *b;

So b is a pointer to a const pointer to an int. With an example:

int main(int argc, char **argv) {
    int i = 5;
    int *ip = &i;
    int * const const * b = &ip;

    (**b)++; /* legal */
    (*b)++; /* illegal */
    (b)++; /* legal */

    return 0;
}