相互引用的结构

Question

I have two structs that need to reference each other, however whichever one I put first throws and error because I am using an unidentified type.

typedef struct _BLOCK
{
    int size;
    int offset;
    struct _BLOCK *nextBlock;
    struct _BLOCK *prevBlock;
    Pool* parent;  //here
} Block;

typedef struct _POOL
{
    int size;
    void* memory;
    Block* Allocated;
    Block* Unallocated;
} Pool;

any ways to resolve this?

Answer 1

You can use forward declaration.

typedef struct _POOL Pool;

typedef struct _BLOCK
{
    int size;
    int offset;
    struct _BLOCK *nextBlock;
    struct _BLOCK *prevBlock;
    Pool* parent;
} Block;

struct _POOL
{
    int size;
    void* memory;
    Block* Allocated;
    Block* Unallocated;
};