数据结构-双向链表的创建、插入和删除
双向链表是数据结构中重要的结构，也是线性结构中常用的数据结构，双向指针，方便用户从首结点开始沿指针链向后依次遍历每一个结点，结点的前驱和后继查找方便。
#include <stdio.h>
#include <stdlib.h>
//双向链表结点的定义
typedef struct dbnode
{
int data;
struct dbnode *prio, *next;
}DbNode, linkdblist;
//创建双向链表
DbNode *creatlist(void)
{
linkdblist *p, *q, *head;
q = p = (linkdblist *)malloc(sizeof(linkdblist));
p->next = NULL;
head = q;
p = (linkdblist *)malloc(sizeof(linkdblist));
scanf("%d", &p->data);
while (p->data != -1)
{
q->next = p;
p->prio = q;
q = p;
p = (linkdblist *)malloc(sizeof(linkdblist));
scanf("%d", &p->data);
}
q->next = NULL;
return head;
}
//输出双向链表
void print(linkdblist *head)
{
linkdblist *p;
p = head->next;
if (p == NULL)
printf("空链表！\n");
while (p != NULL)
{
printf("%d ", p->data);
p = p->next;
}
}
//向双向链表中的第i个位置插入一个结点x
void insertdblist(linkdblist *head, int x, int i)
{
linkdblist *p, *q = head;
if (i == 1)
q = head;
else
{
q = q->next;
int c = 1;
while ((c<i - 1) && (q != NULL))
{
q = q->next;
c++;
}
}
if (q != NULL && q->next != NULL)
{
p = (linkdblist *)malloc(sizeof(linkdblist));
p->data = x;
p->prio = q;
p->next = q->next;
q->next = p;
q->next->prio = p;
}
else
printf("找不到插入的位置！");
}
//删除双向链表中指定位置上的一个结点
void deletelinkdblist(linkdblist *head, int i)
{
linkdblist *p, *q = head;
if (i == 1)
q = head;
else
{
q = q->next;
int c = 1;
while (c < i - 1 && q != NULL)
{
q = q->next;
c++;
}
}
if (q != NULL && q->next != NULL)
{
p = q->next;
p->prio = q;
p->prio->next = p->next;
p->next->prio = p->prio;
free(p);
}
else if (q->next == NULL)
{
p = q;
p->prio->next = NULL;
free(p);
}
else
printf("没有找到待删除的结点");
}
//双向链表的主函数
void main()
{
linkdblist *head;
head = creatlist();
print(head);
printf("\n\n====向双向链表的某位置插入一个值====\n");
int num, i;
printf("输入插入的位置：");
scanf("%d", &i);
printf("\n输入插入的值：");
scanf("%d", &num);
insertdblist(head, num, i);
print(head);
printf("\n");
printf("\n\n====删除双向链表的某位置上的一个值====\n");
int j;
printf("输入删除的位置：");
scanf("%d", &j);
deletelinkdblist(head, j);
print(head);
system("pause");
printf("\n");
}