Thread: Dereference a member of NULL ?

The following code seems to work, but I don't understand why.
The line:

Code:

zip = &dog->next;

Looks to me like it is de-referencing 'next' member of NULL, which doesn't make a whole lot of sense. Is that what is going on, or I am misunderstanding what is going on here? If so, is that well defined?

Thank you,
Kyle

Code:

#include <stdio.h>

struct foo {
    int value;
    struct foo * next;
};

int main() {
    struct foo baz;
    struct foo *dog;
    struct foo **zip;
    baz.next = NULL;
    zip = &baz.next;
    dog = *zip;
    zip = &dog->next;
    return(0);
}

So what is it doing then?
dog = Pointer to NULL
so dog->next is....?

Ah, that makes sense to me! Thank you!