C: pointer to struct in the struct definition

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

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

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


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

typedef struct A A;

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

Edit: As others have mentioned, without the forward declaration 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.

Structures in C++, , you simply precede the name of the instance with a *. We have already learned that a pointer is a variable which points to the address of another variable of any data type like int, char, float etc. Similarly, we can have a pointer to structures, where a pointer variable can point to the address of a structure variable. Here is how we can declare a pointer to a structure variable. 1


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

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

Struct Definition, What is the difference between struct and typedef struct in C? While declaring the function, we passed the pointer of the copy 'st' of the structure variable 's' in its parameter. Since the pointer is of a variable of type structure named student, we wrote 'struct student' before the name of the pointer in the argument of the function.


You are missing the struct before the A*

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

C/C++ Syntax Reference, You can define the typedef and forward declare the struct first in one statement, and then define the struct in a subsequent definition. typedef  You can define pointers to structures in the same way as you define pointer to any other variable − struct Books *struct_pointer; Now, you can store the address of a structure variable in the above defined pointer variable. To find the address of a structure variable, place the '&'; operator before the structure's name as follows − struct_pointer = &Book1;


You can go without forward declaration:

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

Difference between 'struct' and 'typedef struct' in C++ program?, We have already learned that a pointer is a variable which points to the address of another variable of any data type like int , char , float etc. Similarly, we can  C++ Pointers to Structure In this article, you'll find relevant examples that will help you to work with pointers to access data within a structure. A pointer variable can be created not only for native types like ( int , float , double etc.) but they can also be created for user defined types like structure .


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

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

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).

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.

C: pointer to struct in the struct definition, In this tutorial, you'll learn to use pointers to access members of structs in C programming. You will also learn to dynamically allocate memory of struct types. 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


Pointer to a Structure in C, Define a new struct type representing the structure. Declare variables of the struct type; Use DOT notation to access individual field values  is indeed a definition but it is a definition of a pointer to your (earlier declared) struct. It declares the name 'list' and it also reserves memory for the address that may point to an object of your struct after it is defined. So it does not in fact define the actual struct. It does not create an object described by your structure — it does not reserve/allocate memory for such an object.


C structs and Pointers (With Examples), Review: (1) reference (pointer) variables and (2) user-defined types (struct). Recall: Reference data type: dataType* varName ;. define a variable varName that can hold an address of a variable of type To compile: gcc struct-ref1.c; To run: . In the above example, n number of struct variables are created where n is entered by the user. To allocate the memory for n number of struct person, we used, ptr = (struct person*) malloc(n * sizeof(struct person)); Then, we used the ptr pointer to access elements of person.


CS31: Intro to C Structs and Pointers, The structure variables can be a normal structure variable or a pointer variable to access the data. You can learn below concepts in this section. Structure within  Function Pointer in Struct Stuct in C used to represent data structure elemenst, such as student data structure. Struct can contian varible from simple data type and others from complex ones. complex data type such as varible of function pointer.