双向链表的基本操作

#include <stdio.h>
#include <stdlib.h>
 
struct node
{
    int num;
    struct node * next;
};
 
typedef struct node Node;
typedef Node * Link;
 
 //释放节点
void Release(Link * head)
{
    Link p;
 
    while ((*head)->next != *head)
    {
        p = (*head)->next;
        (*head)->next = p->next;
        free(p);
    }
    
    p = *head;
    *head = NULL;
    free(p);
}
 
 //函数功能：创建节点
int Node_creat(Link * new_node)
{
    int n = 0;
 
    do
    {
        *new_node = (Link)malloc(sizeof(Node));
 
        n++;
 
        if (n == 10)
        {
            return 0; 
        }
 
    }while(!*new_node);
 
    return -1;
}
 
 //函数功能：创建链表
void Link_creat(Link * head)
{
    if (!Node_creat(head))
    {
        printf("创建失败！\n");
        exit(-1);
    }
 
    (*head)->next = *head;
}
 
 //函数功能：插入节点：头插
void Link_insert_head(Link head,Link new_node)
{
        new_node->next = head->next;
        head->next = new_node;
}
 
 //函数工能：插入节点：尾插
void Link_insert_tail(Link head,Link new_node)
{
    Link p;
 
    p = head;
 
    while (p->next != head)
    {
        p = p->next;
    }
 
    new_node->next = p->next;
    p->next = new_node;
}
 
 //函数功能：删除指定数据的节点
void Link_delete(Link head,int date)
{
    Link p,q;
 
    p = head;
 
    while(p->next != head)
    {
        if (p->next->num == date)
        {
            q = p->next;
            p->next = q->next;
            free(q);
            return;
        }
       p = p->next;
    }
}
 
 //函数功能：释放节点
void Link_empty(Link head)
{
    Link p;
 
    while (head->next != head)
    {
        p = head->next;
        head->next = p->next;
        free(p);
    }
}
 
 //函数功能：打印链表
void Link_display(Link head)
{
 
    if (head == NULL)
    {
        printf("链表已释放\n");
        return;
    }
 
    if (head->next == head)
    {
        printf("链表为空\n");
        return;
    }
 
    Link p;
 
    p = head->next;
 
    while ( p != head)
    {
        printf("%d\n",p->num);
        p = p->next;
    }
}
 
int main()
{
    int i;
 
    Link head,new_node;
 
    Link_creat(&head);
 
    for (i = 0; i < 10; i++ )
    {
        if (!Node_creat(&new_node))
        {
            Release(&head);
            printf("创建失败！\n");
            exit(-1);
        }
 
        new_node->num = i + 1;
 
        //Link_insert_head(head,new_node);
        Link_insert_tail(head,new_node);
    }
 
    Link_display(head);
 
    Link_delete(head,10);
 
    Link_display(head);
    
    Link_empty(head);
 
    Link_display(head);
 
    Release(&head);
 
    Link_display(head);
 
    return 0;
}