数据结构之---c语言实现双向链表操作

#include<stdio.h>
#include<stdlib.h>
typedef int ElemType;
typedef struct DoubleLinkedList
{
     ElemType data;
     struct DoubleLinkedList *pre;
     struct DoubleLinkedList *next;
}DlinkedList_Node;  

//建立链表
DlinkedList_Node* create_dlink()
{
   DlinkedList_Node *head,*p,*s;
   int x;
   head = (DlinkedList_Node*)malloc(sizeof(DlinkedList_Node));
   p = head;
   while(1)
   {
       printf("请输入要保存的节点， 以0结束输入:\n");
       scanf("%d",&x);
       if(x != 0)
       {
          s = (DlinkedList_Node*)malloc(sizeof(DlinkedList_Node));
          s ->data = x;
          s-> pre = p;
          p->next = s;
          p=s;
       }
       else
       {
          printf("\n数据输入结束\n");
          break;
       }
    }
    p->next = NULL;
    head = head ->next;
    head->pre = NULL;
    return head;
}  

//顺序、反序打印链表
void print_dlink(DlinkedList_Node *head)
{
	DlinkedList_Node *p,*s;
    p = head;
    printf("正序输出双向链表中的节点：\n");
    while(p)
    {
        printf("%d ",p->data);
        s = p;
        p = p->next;
    }
    printf("\n 逆序输出双向链表中的节点: \n");
    while(s)
    {
        printf("%d ",s->data);
        s = s->pre;
    }
    printf("\n \n");
}  

//删除所指定的元素的节点
DlinkedList_Node* delete_dlinkedlist_node(DlinkedList_Node *head,int i)
{
    DlinkedList_Node *p;
    p = head;
    if(p->data == i)
    {
        head = p->next;
        head->pre = NULL;
        free(p);
        return head;
    }
    while(p)
    {
        if(p->data == i)
        {
         	p->pre->next = p->next;
            p->next->pre = p->pre;
            free(p);
            return head;
         }
         p = p->next;
     }
     printf("抱歉输入数据有误！，没有找到想要删除的数据\n");
     return head;
 }

//插入一个结点
DlinkedList_Node* insert_dlinkedlist_node(DlinkedList_Node *head,int i)
{  

   DlinkedList_Node *p,*temp;
   p = head;
   temp = (DlinkedList_Node*)malloc(sizeof(DlinkedList_Node));
   temp ->data = i;
   if(i < p->data)//比头结点数据小，插入到链表头部
   {
       head = temp;
       head->next = p;//此处p为原来的head
       head->pre = NULL;
       p->pre = head;//此处p为原来的head
       return head;
    }

    while(p != NULL && i > p->data)//寻找合适的插入位置
    {
       p = p->next;
    }
    if(i < p->data)//在链表中间某处找到合适插入位置
    {
        temp ->next = p;
        temp ->pre = p->pre;
        p ->pre->next = temp;
        p ->pre = temp;
        return head;
     }
	else//没有找到合适的位置，只有将数据插入到链表尾部
     {
         p->next = temp;  //遍历到链表尾部，p==NULL
         temp ->pre = p;
         temp ->next = NULL;
         return head;
      }
}  

int main()
{
    DlinkedList_Node *head;
    head = create_dlink();
    print_dlink(head);
    return 0;
}