Question

I have code with circular dependency.

old a.h file:

#ifndef A_H
#define A_H

#include "b.h"

typedef struct {
    b_t *test;
} a_t;

#endif

old b.h file:

#ifndef B_H
#define B_H

#include "a.h"

typedef struct {
    a_t *test;
} b_t;

#endif

I’ve just wanted to know if my solution is “proper way” to solve that problem. I want produce nice and clear code.

new a.h file:

#ifndef A_H
#define A_H

#include "b.h"

typedef struct b_t b_t;

struct a_t {
    b_t *test;
};

#endif

new b.h file:

#ifndef B_H
#define B_H

#include "a.h"

typedef struct a_t a_t;

struct b_t {
    a_t *test;
};

#endif

Answer 1

A problem with your approach is that the typedef for a_t is in the b.h, and vice versa.

A somewhat cleaner way would be to keep your typedef with the struct, and use structure tags in the declarations, like this:

a.h

#ifndef A_H
#define A_H

struct b_t;

typedef struct a_t {
    struct b_t *test;
} a_t;

#endif

b.h

#ifndef B_H
#define B_H

struct a_t;

typedef struct b_t {
    struct a_t *test;
} b_t;

#endif