Question

Alright, this is a really quick question: why does this first block of code compile, but the second one doesn’t? They seem like they should be equivalent, since all that I change is the variable declaration/references.

First:

int memberStudents(struct studentType x, Snodeptr students, Snodeptr *s) {
    Snodeptr p = *s;

    while (p->next != NULL) {
        if (strcmp(x.sid, p->student.sid) == 0)
            return 1;

        p = p->next;
    }

    return 0;
}

Second:

int memberStudents(struct studentType x, Snodeptr students, Snodeptr *s) {
    while (s->next != NULL) {
        if (strcmp(x.sid, s->student.sid) == 0)
            return 1;

            s = s->next;
    }

    return 0;
}

I want to change the Snodeptr s so that it points to the proper place, but when I try the second block of code I get an error saying there is a request for member ‘next’ in something not a struct or union.

Answer 1

Snodeptr *s and Snodeptr p are different types, and therefore behave differently

try (*s)->next