带头结点的双向循环链表----------C语言

 /*****************************************************
 Author：Simon_Kly    Version:0.1    Date: 20170520
 Description：带头结点的双向循环链表
 Mail: [e-mail]
 Funcion List:
 *****************************************************/

 #include <stdio.h>
 #include <stdlib.h>

 typedef struct node
 {
     int data;
     struct node *prior, *next;
 }Node, *Link;

 void is_malloc_ok(Link head)
 {
     if (head == NULL)
     {
         printf("malloc is error!\n");
         exit(-);
     }
 }

 /*创建链表*/
 void create_link(Link * head)
 {
     *head = (Link)malloc(sizeof(Node));

     is_malloc_ok(*head);

     (*head)->next = (*head)->prior = *head;//让其指向自己
 }

 /*创建节点*/
 void create_node(Link * new_node)
 {
     *new_node = (Link)malloc(sizeof(Node));
     is_malloc_ok(*new_node);
 }

 /*插入节点(头插)*/
 void insert_node_head(Link head, Link new_node)
 {
     new_node->prior = head;
     new_node->next = (head)->next;
     (head)->next->prior = new_node;
     (head)->next = new_node;
 }

 /*插入节点(尾插)*/
 void insert_node(Link * head, Link new_node)
 {
     Link p = NULL;

     p = *head;
     while (p->next != *head)
     {
         p = p->next;
     }

     new_node->prior = p;
     new_node->next = p->next;
     p->next->prior = new_node;
     p->next = new_node;
 }

 /*输出链表*/
 void out_link(Link head)
 {
     Link p = NULL;
 #if 0
     if (head->next == head)
     {
         printf("link is empty\n");
         return ;
     }
 #endif

     if (head == NULL)
     {
         printf("link is empty\n");
         return ;
     }

     p = (head)->next;

     while (p != head)
     {
         printf("%d\n", p->data);
         p = p->next;
     }
     putchar();
 }

 /*变成空链*/
 void make_empty(Link * head)
 {
     Link p = NULL;

     p = (*head)->next;

     while (*head != (*head)->next)
     {
         (*head)->next = p->next;//head移动
         free(p);//释放head之前的节点
         p = (*head)->next;
     }
 }

 /*释放链表*/
 void release_link(Link * head)
 {
     make_empty(head);

     free(*head);

     *head = NULL;
 }

 /*删除节点*/
 void delete_node(Link * head, int data)
 {
     Link p = NULL;

     p = (*head)->next;

     if (p == *head)//空链
     {
         printf("link is empty!\n");
         return ;
     }

     /*非空链*/
     while (p != *head && p->data != data)
     {
         p = p->next;//找那个节点
     }

     if (p == *head)//找一圈没找到
     {
         printf("No such node!\n");
         return ;
     }
     else//找到并改变指向
     {
         p->prior->next = p->next;
         p->next->prior = p->prior;

         free(p);
     }
 }

 void insert_node_seq(Link * head, Link new_node)
 {
     Link p = NULL;

     p = (*head);

     while (p->next != *head && new_node->data < p->next->data)//找到该位置的前一个位置
     {
         p = p->next;
     }
 #if 0
     if (p == *head)//找到尾部
     {
         new_node->prior = p->prior;
         new_node->next = p;
         p->prior->next = new_node;
         p->prior = new_node;
         return ;
     }
 #endif
     new_node->prior = p;
     new_node->next = p->next;
     p->next->prior = new_node;
     p->next = new_node;

 }

 int main()
 {
     int i;
     Link head = NULL;
     Link new_node = NULL;
     create_link(&head);

     out_link(head);

     for (i = ; i < ; i++)
     {
         create_node(&new_node);
         new_node->data = i + ;
     //    insert_node(&head, new_node);
         insert_node_head(head, new_node);
     }

     out_link(head);

 #if 1
     printf("please input i\n");
     scanf("%d", &i);
     putchar();
     create_node(&new_node);
     new_node->data = i;
     insert_node_seq(&head, new_node);
     out_link(head);
 #endif

 #if 0
     delete_node(&head, );
     out_link(head);
 #endif
     release_link(&head);
     out_link(head);
     return ;
 }