在结构定义中指向struct的指针。

How can I have a pointer to the next struct in the definition of this struct:

如何在这个结构的定义中有指向下一个结构的指针:

typedef struct A {
  int a;
  int b;
  A*  next;
} A;

this is how I first wrote it but it does not work.

这是我第一次写它，但它不起作用。

6 个解决方案

#1

You can define the typedef and forward declare the struct first in one statment, and then define the struct in a subsequent definition.

您可以定义typedef，并在一个状态中首先声明struct，然后在随后的定义中定义struct。

typedef struct A A;

struct A
{
    int a;
    int b;
    A* next;
};

Edit: As others have mentioned, without the forward declaratation the struct name is still valid inside the struct definition (i.e. you can used struct A), but the typedef is not available until after the typedef definition is complete (so using just A wouldn't be valid). This may not matter too much with just one pointer member, but if you have a complex data structure with lots of self-type pointers, may be less wieldy.

编辑:正如其他人所提到的，在没有前向声明的情况下，struct名称在struct定义中仍然有效(例如，您可以使用struct A)，但是类型定义在typedef定义完成之后才可用(因此只使用A是无效的)。对于一个指针成员来说，这可能不太重要，但是如果您有一个复杂的数据结构，其中有许多自类型指针，那么它可能就不那么笨重了。

#2

In addition to the first answer, without a typedef and forward declaration, this should be fine too.

除了第一个答案之外，没有类型定义和转发声明，这也应该没问题。

struct A 
{ 
    int a; 
    int b; 
    struct A *next; 
};

#3

You are missing the struct before the A*

你错过了A*之前的结构

  typedef struct A {
    int a;
    int b;
    struct A* next;
  } A;

#4

You can go without forward declaration:

你可以不提前声明:

struct A {
    int a;
    int b;
    struct A *next;
};

#5

Please, you're in C, not C++.

拜托，你用的是C语言，不是c++。

If you really must typedef a struct (and most programmers that I work with would not¹), do this:

如果你真的必须类型定义一个结构体(和大多数程序员,我的工作不会¹),这样做:

typedef struct _A {
    int a;
    int b;
    struct _A *next;
} A;

to clearly differentiate between _A (in the struct namespace) and A (in the type namespace).

要明确区分_A(在struct名称空间中)和A(在类型名称空间中)。

¹typedef hides the size and storage of the type it points to ― the argument (and I agree) is that in a low-level language like C, trying to hide anything is harmful and counterproductive. Get used to typing struct A whenever you mean struct A.

¹typedef隐藏的大小和存储类型它指向——(我认为)的观点认为,在一个低级语言(如C),试图隐瞒什么是有害的,会适得其反。习惯输入struct A，只要你指的是struct A。

#6

typedef struct {
 values
} NAME;

This is shorter way to typedef a struct i think its the easiest notation, just don't put the name infront but behind.

这是定义结构的一种更短的方式我认为这是最简单的符号，只是不要把名字放在前面而放在后面。

you can then call it like

你可以这样称呼它

NAME n;  

NAME *n; // if you'd like a ptr to it.

Anything wrong with this approach?

这种方法有什么问题吗?

#1