如何定义包含指向自身的指针的typedef结构？

I am writing a LinkedList in C, the below code represent my Node definition.

我在C中编写LinkedList，下面的代码表示我的Node定义。

typedef struct {
    int value;
    struct Node* next;
    struct Node* prev;
} Node;

I understand (or think that I do) that struct Node not the same as typedef struct Node. Granted my code compiles and runs as it's supposed to, however, I get a lot of warnings when assigning next and prev (warning: assignment from incompatible pointer type). I am guessing that this has to do with how I'm defining them in the Node structure. I uploaded the full source here

我理解（或者认为我这样做）struct Node与typedef struct Node不同。虽然我的代码编译并按照预期运行，但是，在分配next和prev时会收到很多警告（警告：从不兼容的指针类型分配）。我猜这与我在Node结构中定义它们的方式有关。我在这里上传了完整的资源

So, if that is indeed the problem, how should I define next and prev inside the typedef struct Node?

那么，如果这确实是问题，我应该如何在typedef struct Node中定义next和prev？

I was worried this may be a repost, but couldn't quite find what I was looking for. Thanks.

我担心这可能是一个转贴，但无法找到我想要的东西。谢谢。

2 个解决方案

#1

You need to do it in this order:

您需要按此顺序执行此操作：

typedef struct Node Node;

struct Node
{
  int value;
  Node *next;
  Node *prev;
};

That doesn't do exactly what you asked, but it solves the problem and is how this generally is done. I don't think there's a better way.

这并没有完全符合你的要求，但它解决了问题，并且通常是这样做的。我不认为有更好的方法。

This kind of forward declaration has a second usage, in data hiding. If the list was implemented in a library, you could have just the typedef in the public header, along with functions like:

这种前向声明在数据隐藏方面有第二种用法。如果列表是在库中实现的，那么您可以在公共头中使用typedef，以及以下函数：

Node * list_new(void);
Node * list_append(Node *head, Node *new_tail);
size_t list_length(const Node *head);

This way, users of the library don't have easy access to the internals of your library, i.e. the fields of the Node structure.

这样，库的用户就无法轻松访问库的内部，即Node结构的字段。

#2

Another acceptable way and with the least change to OP's code is the following:

另一种可接受的方式，对OP代码的更改最少如下：

typedef struct NodeT {
    int value;
    struct NodeT * next;
    struct NodeT * prev;
} Node;

Note the introduction of NodeT and its usage in next and prev until Node is available.

请注意NodeT的介绍及其在next和prev中的用法，直到Node可用。

#1