在不阻止关键字struct的情况下，对结构进行typedef

Question

Suppose this scheme:

/* avl.c */

typedef struct avl {
    void *data;
    int height;
    struct avl *left, *right;
} node;

/* avl.h */

struct avl; /* opaque */

I want to use:

struct node *root;

instead of

node *root;

in avl.c, but for now the best I have found is:

struct avl {
    void *data;
    int height;
    struct avl *left, *right;
};

#define node avl

Another way?

Answer 1

Then you should remove the typedef :

struct node{
    void *data;
    int height;
    struct node *left, *right;
} 

Answer 2

Without using the preprocessor, you must give the struct and the typedef the same name for that to work, eg

  typedef struct node {
        void *data;
        int height;
        struct node *left, *right;
    } node;

So now struct node and node is the same thing.

Answer 3

There is no other way than using macros to do that. The reason is that struct tags have their own namespace . Different names in the tag namespace always refer to different types, even if the structs contain the same member types. Proper aliasing of types can only be done with typedefs, which are defined to be aliases and not separate types.

Answer 4

struct avl {
    void *data;
    int height;
    struct avl *left, *right;
};

typedef struct alv node;

struct avl* ptr1; //valid
avl* ptr1; //not valid
struct node* ptr2;  //valid
node* ptr3;  //also valid

That forces you to use struct avl , that doesn't force you to use struct node , but you can if you want to.