Typedef函数指针编译问题 [英] Typedef function pointer compilation problem

问题描述

我试图用结构指针的参数声明一个函数指针（这也是一个typedefed结构）但是在编译时，我得到以下错误



typedef'callback_fn_ptr'被初始化（改为使用decltype）

myStruct未在此范围内声明

ptr未在此范围内声明。



这是我的声明。



struct A

{

int Z;

};

I am trying to declare a function pointer with argument of a structure pointer(which is also a typedefed structure) but while compiling, i am getting below error

"typedef 'callback_fn_ptr' is initialized (use decltype instead)
myStruct was not declared in this scope
ptr was not declared in this scope."

Here is my declaration.

struct A
{
int Z;
};

typedef struct A myStruct;

无效（* callback_fn_ptr）（myStruct * ptr）;



在cpp文件中，函数指针变量创建如下。



callback_fn_ptr my_fun_ptr;



我尝试过：



当我将typdef结构移除到没有typedef的普通结构时，则看不到问题。



void（* callback_fn_ptr）（struct A * ptr）; //编译时没问题



有人可以帮忙吗？

void (*callback_fn_ptr)(myStruct *ptr);

In cpp file, function pointer variable is created as below.

callback_fn_ptr my_fun_ptr;

What I have tried:

When i remove the typdef structure to a normal structure without typedef then issue is not seen.

void (*callback_fn_ptr)(struct A *ptr); //no problem during compilation

can someone please help?

推荐答案

我错过了<代码中code> typedef ：

I'm missing a typedef in your code:

struct A
{
    int Z;
};
typedef struct A myStruct;
// Missing typedef here
//void (*callback_fn_ptr)(myStruct *ptr);
typedef void (*callback_fn_ptr)(myStruct *ptr);

// ...
callback_fn_ptr my_fun_ptr;

但是，您也可以使用 typedef 'ed struct代替：

However, you may also use a typedef'ed struct instead:

typedef struct 
{
    int Z;
} myStruct;
typedef void (*callback_fn_ptr)(myStruct *ptr);

// ...
callback_fn_ptr my_fun_ptr;

以上两个片段都是用GCC编译的。

Both above snippets compile with GCC.

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