此错误容易出现在**指针访问时，解决方法是使用（）括起来，原因主要是类型不匹配。
#include <stdio.h>
#include <stdlib.h>
struct ac{
int data;
struct ac *next;
};
void address(struct ac *p)
{
struct ac *next, **scan;
struct ac pa;
pa.data = 10;
pa.next = &pa;
next = p->next;
scan = &p->next;
printf("pa = %p\n", &pa);
printf("pa.a = %p\n", &pa.data);
printf("pa.next = %p\n\n", &pa.next);
printf("next = %p\n", next); // 一级指针指向地址 p->next
printf("scan = %p\n", scan); // 一级指针地址 &p->next
printf("*scan = %p\n\n", *scan); // 一级指针指向地址 p->next
printf("p->next = %p\n", p->next); // 一级指针指向地址 p->next
printf("p->next->next = %p\n", p->next->next); // 一级指针指向地址 p->next->next
printf("p->next->next->next = %p\n\n", p->next->next->next); // 一级指针指向地址 p->next->next->next
printf("&p->next->next = %p\n", &p->next->next); // 一级指针地址
printf("&(p->next)->next = %p\n", &(p->next)->next); // 一级指针地址
printf("&(p->next->next) = %p\n\n", &(p->next->next)); // 一级指针地址
printf("(*scan)->next = %p\n\n", (*scan)->next); // 一级指针指向地址 p->next->next
//printf("*scan->next = %p\n", *scan->next); // error: '*scan' is a pointer; did you mean to use '->'?
//printf("scan->next = %p\n", scan->next); // error: '*scan' is a pointer; did you mean to use '->'?
if ((*scan)->next == next) {
printf("ditto\n\n");
}
p->next->next = &pa;
printf("next = %p\n", next); // 一级指针指向地址 p->next
printf("scan = %p\n", scan); // 一级指针地址 &p->next
printf("*scan = %p\n", *scan); // 一级指针指向地址 p->next
printf("(*scan)->next = %p\n", (*scan)->next); // 一级指针指向地址 p->next->next
//printf("*scan->next = %p\n", *scan->next); // error: '*scan' is a pointer; did you mean to use '->'?
printf("p->next->next = %p\n", p->next->next); // 一级指针指向地址 p->next->next
}
int main()
{
struct ac p;
p.data = 10;
p.next = &p;
printf("p = %p\n", &p);
printf("p.a = %p\n", &p.data);
printf("p.next = %p\n\n", &p.next);
address(&p);
return 0;
}