声明相互使用的结构体和函数引用

发布于 2024-10-20 14:13:24 字数 803 浏览 1 评论 0原文

我需要在旧的 C 中声明一个 (typedef'd) 结构和一个 (typedef'd) 函数引用。这是我的代码：

typedef void (*monitor_calback)(monitor_data*, short int, short int, void*);

typedef struct
{
    int port;
    unsigned char port_state;

    monitor_calback cb_high[8];
    void *cb_high_data[8];
    monitor_calback cb_low[8];
    void *cb_low_data[8];
} monitor_data;

但是它当然不会编译，因为我们不知道函数调用时的结构声明引用。

我已经得到了这个，但它看起来有点乱而且有点难以阅读。

struct _monitor_data;

typedef void (*monitor_calback)(struct _monitor_data*, short int, short int, void*);

typedef struct _monitor_data
{
    int port;
    unsigned char port_state;

    monitor_calback cb_high[8];
    void *cb_high_data[8];
    monitor_calback cb_low[8];
    void *cb_low_data[8];
} monitor_data;

有没有更好的方法来做到这一点？

原文

I need to declare a (typedef'd) structure and a (typedef'd) function reference in pain old C. This is my code:

typedef void (*monitor_calback)(monitor_data*, short int, short int, void*);

typedef struct
{
    int port;
    unsigned char port_state;

    monitor_calback cb_high[8];
    void *cb_high_data[8];
    monitor_calback cb_low[8];
    void *cb_low_data[8];
} monitor_data;

But of course it doen't compile because we don't know about the structure when the function reference is declared.

I have gotten this but it looks kinda messy and is a little hard to read.

struct _monitor_data;

typedef void (*monitor_calback)(struct _monitor_data*, short int, short int, void*);

typedef struct _monitor_data
{
    int port;
    unsigned char port_state;

    monitor_calback cb_high[8];
    void *cb_high_data[8];
    monitor_calback cb_low[8];
    void *cb_low_data[8];
} monitor_data;

Are there any better ways to do this?

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鸵鸟症 2024-10-27 14:13:24

您可以在定义结构之前对其进行 typedef：

typedef struct _monitor_data monitor_data;

typedef void (*monitor_calback)(monitor_data*, short int, short int, void*);

struct _monitor_data
{
    int port;
    unsigned char port_state;

    monitor_calback cb_high[8];
    void *cb_high_data[8];
    monitor_calback cb_low[8];
    void *cb_low_data[8];
};

只要您在完全定义 struct _monitor_data 之前不尝试引用 monitor_data 的内部结构，就可以正常工作。对于您的 monitor_callback 定义，编译器需要知道的是 monitor_data * 是一个指向某个内容的指针，因此只要编译器知道 monitor_callback 就可以了monitor_data 存在。

这种构造是在 C 中定义不透明类型的标准方法，您只需取消类型的不透明，而不是使其保持不透明。

You can typedef a struct before defining it:

typedef struct _monitor_data monitor_data;

typedef void (*monitor_calback)(monitor_data*, short int, short int, void*);

struct _monitor_data
{
    int port;
    unsigned char port_state;

    monitor_calback cb_high[8];
    void *cb_high_data[8];
    monitor_calback cb_low[8];
    void *cb_low_data[8];
};

This will work fine as long as you don't try to reference the internal structure of monitor_data before struct _monitor_data is fully defined. All the compiler needs to know for your monitor_callback definition is that monitor_data * is a pointer to something so monitor_callback is fine as long as the compiler knows that monitor_data exists.

This sort of construct is the standard approach for defining opaque types in C, you'd just be un-opaquing your type rather than leaving it opaque.

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慕烟庭风 2024-10-27 14:13:24

您可以更喜欢以下内容，具体取决于口味：

    #define monitor_data struct _monitor_data
    typedef void (*monitor_calback)(monitor_data*, short int, short int, void*);

    typedef struct _monitor_data
    {
        int port;
        unsigned char port_state;

        monitor_calback cb_high[8];
        void *cb_high_data[8];
        monitor_calback cb_low[8];
        void *cb_low_data[8];
    };

You could prefer the following, depends on taste tho:

    #define monitor_data struct _monitor_data
    typedef void (*monitor_calback)(monitor_data*, short int, short int, void*);

    typedef struct _monitor_data
    {
        int port;
        unsigned char port_state;

        monitor_calback cb_high[8];
        void *cb_high_data[8];
        monitor_calback cb_low[8];
        void *cb_low_data[8];
    };

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