如何访问此结构体的成员

Question

我有一个结构，大致如下：

typedef struct first_struct {
  const char *name;             /**name */
  second_struct_t *priv; /**private data */
} first_struct_t;

我只需使用

即可访问

priv

first_struct_t first;
printf("priv at %p\n", first->priv);

second_struct

大致定义如下

typedef struct second_struct second_struct_t;


struct second_struct {
  uint8_t base;
  internal_type *target_member;
};

现在我想了解如何访问

target_member

。不幸的是，

first->priv->target_member

不起作用，因为我无法正确包含必要的标头，因为类型已转发。

我想过使用

addressof

，识别

target_member

的偏移量，但没有运气。

当然，一旦我有权访问

target_member

，我想访问其成员并打印值。

关于如何解决这个问题有什么建议吗？

Answer 1

struct second_struct {
  uint8_t base;
  internal_type *target_member;
};

typedef struct second_struct second_struct_t;

typedef struct first_struct {
  const char *name;             /**name */
  second_struct_t *priv; /**private data */
} first_struct_t;


void foo(void) {
   first_struct_t first; // note this is not a pointer
   first_struct_t *pf = &first; // this is pointer

   second_struct_t second; // just a buffer on the stack
   first.priv = &second; // pointer should point somewhere

   printf("priv at %p\n", first.priv);
   printf("target_member at %p\n", first.priv->target_member);

   printf("priv at %p\n", pf->priv);
   printf("target_member at %p\n", pf->priv->target_member);
}