我得到“从不兼容的指针类型‘ListNode *’对‘struct ListNode *’的赋值”，即使我声明了 `typedef struct { … } ListNode;`

Question

我正在尝试使用 C 创建一个链接列表，当我尝试编译它时，我不断收到此错误，

warning: assignment to ‘struct ListNode *’ from incompatible pointer type ‘ListNode *’ [-Wincompatible-pointer-types]

这些是我的结构：

typedef struct {
    void* data;
    struct ListNode* next;
    struct ListNode* prev;
} ListNode;

typedef struct {
    ListNode* head;
    ListNode* tail;
    int size;
} LinkedList;

完整的警告列表如下所示：

linkedList.c:26:21: warning: assignment to ‘struct ListNode *’ from incompatible pointer type ‘ListNode *’ [-Wincompatible-pointer-types]
   26 |         newNd->next = list->head;
      |                     ^
linkedList.c: In function ‘printList’:
linkedList.c:47:16: warning: assignment to ‘ListNode *’ from incompatible pointer type ‘struct ListNode *’ [-Wincompatible-pointer-types]
   47 |         currNd = currNd->next;
      |                ^
linkedList.c: In function ‘removeStart’:
linkedList.c:59:16: warning: assignment to ‘ListNode *’ from incompatible pointer type ‘struct ListNode *’ [-Wincompatible-pointer-types]
   59 |     list->head = temp->next;
      |                ^
linkedList.c: In function ‘insertLast’:
linkedList.c:88:18: warning: assignment to ‘ListNode *’ from incompatible pointer type ‘struct ListNode *’ [-Wincompatible-pointer-types]
   88 |             temp = temp->next;
      |                  ^
linkedList.c:90:20: warning: assignment to ‘struct ListNode *’ from incompatible pointer type ‘ListNode *’ [-Wincompatible-pointer-types]
   90 |         temp->next = newNd;
      |                    ^
linkedList.c: In function ‘removeLast’:
linkedList.c:109:14: warning: assignment to ‘ListNode *’ from incompatible pointer type ‘struct ListNode *’ [-Wincompatible-pointer-types]
  109 |         curr = curr->next;
      |              ^

如果需要更多信息，我很乐意添加更多信息。

Answer 1

在定义 ListNode 时，您创建了一个匿名结构的 typedef。因此它与 struct ListNode 不同。你需要做的是

typedef 结构ListNode { …… } 列表节点；

Answer 2

如果您希望将指向结构的指针作为该结构的成员，则它需要在 typedef 之前有一个名称。

typedef struct ListNode {
    void* data;
    struct ListNode* next;
    struct ListNode* prev;
} ListNode;

或者，从类型定义开始：

typedef struct ListNode ListNode;

struct ListNode {
    void* data;
    ListNode* next;
    ListNode* prev;
};

您的结构类型定义为

LinkedList

 不需要这个，因为它不包含指向 

LinkedList

 作为成员的指针。