Typedef用于相互指向的结构

Question

Ansi C allows that two different structs can contain pointers to each other (also shown in structs-that-refer-to-each-other ). I know that this is not a good idea in many circumstances, but that's not the question here. Is it possible to achieve the same using typedef'ed structs?

The code below works just fine.

struct b;
typedef struct a {
    struct b *bb;
} A;
typedef struct b {
    struct a *aa;
} B;

But using type "B" it fails

typedef struct b B;
typedef struct a {
    B *bb;
} A;
typedef struct b {
    A *aa;
} B;

with

error: redefinition of typedef 'B'

Is it possible to tell the compiler that 'B' will be declared later and use it in the definition of A?

Answer 1

You can do this instead:

typedef struct a A;
typedef struct b B;

struct a {
    B *bb;
};
struct b {
    A *aa;
};

Does this work for you ?

Answer 2

The issue is that you already typedef'd it.

You should do something like this:

struct a;
struct b;
typedef struct a A;
typedef struct b B;

And then you can define struct a and b and use a,b,A*,B* in the definitions of a and b