C的小特點

定義在struct內部的struct,也可以在struct外面使用,與定義在全局的效果是一樣的。

#include <stdio.h>
struct queue_t
{
  int value;
  char key[100];
  struct joint_t
  {
    int prev;
    int next;
  } joint;
};

int main()
{
  struct queue_t queue;
  queue.joint.next = 1;

  struct joint_t joint;
  joint.next = 2;
  printf("%d , %d\n", queue.joint.next, joint.next);
  printf("%d , %d\n", queue.joint.next, joint.next);
  //app_error("ksjfdkj");
}

struct初始化時加={} 可以把struct實例所佔內存初始化爲0

#include <stdio.h>
struct queue_t
{
  int value;
  char key[100];
  struct joint_t
  {
    int prev;
    int next;
  } joint;

};

int main()
{
  struct queue_t queue; //
  struct queue_t queue2 = {}; //全部元素初始化爲0
  printf("%d, %d, %d\n", queue.value, queue.joint.prev, queue.joint.next);
  printf("%d, %d, %d\n", queue2.value, queue2.joint.prev, queue2.joint.next);
}