双向循环链表的操作

#include <stdio.h>

 

struct node

{

    int num;

 

    struct node *prior;

    struct node *next;

};

 

typedef struct node Node;

typedef Node * DLink;

 

void create_d_link(DLink *head)

{

    *head = (DLink)malloc(sizeof(Node));

 

    (*head)->next = *head;

    (*head)->prior = *head;

}

 

void insert_head_node(DLink *newnode,DLink *head)

{

    (*newnode)->next = (*head)->next;

    (*head)->next->prior = *newnode;

 

    (*head)->next = *newnode;

    (*newnode)->prior = *head;

}

 

void insert_tail_node(DLink *newnode, DLink *head)

{

     (*head)->prior->next = *newnode;

     (*newnode)->prior = (*head)->prior;

 

     (*newnode)->next = *head;

     (*head)->prior = *newnode;

}

 

int insert_mid_node(DLink *newnode, DLink *head, int num)

{

     DLink temp = (*head)->next;

     

     while(temp != *head)

     {

         if(temp->num == num)

 {

    (*newnode)->next = temp->next;

    temp->next->prior = *newnode;

 

    temp->next = *newnode;

    (*newnode)->prior = temp;

    return 0;

 }

 

 temp = temp->next;

     }

 

     return -1;

}

 

int delete_node(int num, DLink *head)

{

    DLink temp = (*head)->next;

 

    while(temp != *head)

    {

        if(temp->num == num)

{

    temp->prior->next = temp->next;

    temp->next->prior = temp->prior;

    free(temp);

    temp = NULL;

    return 0;

}

 

temp = temp->next;

    }

 

    return -1;

}

 

void display_d_link(DLink *head)

{

    DLink temp = (*head)->next;

 

    while(temp != *head)

    {

        printf("temp->num = %d\n",temp->num);

temp = temp->next;

    }

}

 

int main()

{

    int i;

    

    DLink head;

    DLink newnode;

 

    create_d_link(&head);

    

    for(i = 0; i < 10; i++)

    {

        newnode = (DLink)malloc(sizeof(Node));

 

newnode->num = i + 1;

 

// insert_head_node(&newnode,&head);

        insert_tail_node(&newnode,&head);

    }

    printf("insert tail:\n");

    display_d_link(&head);

    

    newnode = (DLink)malloc(sizeof(Node));

    newnode->num = 11;

 

    insert_mid_node(&newnode,&head,5);

    printf("mid insert:\n");

    display_d_link(&head);

 

    delete_node(5,&head);

 

    printf("delete node:\n");

    display_d_link(&head);

 

    return 0;

}