嵌入式 Linux C语言（十三）——双链表

一、双链表简介

1、双链表的结构

    双链表是链表的一种，由节点组成，每个数据结点中都有两个指针，分别指向直接后继和直接前驱。

2、双链表的节点

typedef struct data

{

unsigned int id;//学生身份ID

char name[LENGTH];//学生姓名

char subject[LENGTH];//科目

unsigned int score;//分数

}DATA,*PDATA;

 

typedef struct node

{

struct node *prev;

unsigned int num;//节点序号，头节点则保存链表的节点数量

DATA data;//数据

struct node *next;

}Node,*DList;

二、双链表的操作

1、双链表的创建

双链表头结点的创建：

DList dlist_init(void)

{

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

if(NULL == head)

{

fprintf(stderr, "dlist_init function malloc failure.\n");

return NULL;

}

head->next = NULL;

head->prev = NULL;

return head;

}

采用尾部插入节点的方式创建双链表

int dlist_create(DList head, unsigned int num)

{

DList p,r;

r = head;

int i;

for(i = 0; i < num; i++)

{

p = (Node *)malloc(sizeof(Node));//创建新节点

if(NULL == p)

{

fprintf(stderr, "dlist_create function p malloc failed.\n");

return ERROR;

}

p->num = i+1;//将各个节点的序号写入节点成员num

p->data.id = 1000 + i;

strcpy(p->data.name, "scorpio");

strcpy(p->data.subject, "English");

p->data.score = 100;

r->next = p;

p->prev = r;

r = p;

}

r->next = NULL;

head->num = dlist_size(head);//将创建链表的大小写入头结点num成员

return OK;

}

2、双链表的销毁

void dlist_destroy(DList list)

{

DList p;

while(list)

{

p = list->next;

free(list);

list = p;

}

}

3、双链表的节点插入操作

void dlist_insert(DList list, unsigned int i, PDATA data)

{

if(dlist_size(list) < i)

{

fprintf(stdout, "dlist_insert function failed.The list size is too samll.There is no element %u.\n", i);

return ;

}

//创建一个节点

DList p = (Node *)malloc(sizeof(Node));

//利用传入的data结构体的数据对节点的数据域进行初始化

p->data.id = data->id;

strcpy(p->data.name, data->name);

strcpy(p->data.subject, data->subject);

p->data.score = data->score;

//找到节点i

DList r = list->next;

if(NULL == r->next)//链表为空时，直接插入

{

//插入节点到链表

p->next = r->next;

r->next = p;

p->prev = r;

}

else//链表不为空时，先查找插入的位置

{

while(i != r->num)

{

r = r->next;

}

//插入节点到链表

p->next = r->next;

r->next = p;

p->prev = r;

}

//顺延链表节点i后的节点的序号

int n = i + 1;

r = r->next;

while(r->next)

{

r->num = n++;

r = r->next;

}

r->num = n;//尾节点的序号

list->num = dlist_size(list);//将链表的大小写入头结点num成员

}

4、双链表的节点的删除操作

void dlist_delete(DList list, unsigned int i)

{

if(dlist_size(list) < i)

{

fprintf(stdout, "dlist_insert function failed.The list size is too samll.There is no element %u.\n", i);

return ;

}

DList r = list->next;

//查找要删除节点的位置

while(i != r->num)

{

r = r->next;

}

DList p = r->next;

//从链表中删除节点

r->next->next->prev = r;

r->next = r->next->next;

free(p);

//顺延链表节点i后的节点的序号

int n = i;

while(r->next)

{

r->num = n++;

r = r->next;

}

r->num = n;//尾节点的序号

list->num = dlist_size(list);//将创建链表的大小写入头结点num成员

}

5、获取双链表的长度

unsigned int dlist_size(DList list)

{

unsigned int count = 0;

DList p = list->next;

while(p)

{

p = p->next;

count++;

}

return count;

}

6、判断双链表是否为空

int dlist_is_empty(DList list)

{

if(list)

{

fprintf(stdout, "list is no empty.\n");

return 0;

}

else

{

fprintf(stdout, "list is empty.\n");

return 1;

}

}

 

7、遍历双链表

void dlist_traverse(DList list)

{

fprintf(stdout, "list size is %u\n", list->num);

DList p = list->next;//跳过头结点

while(p)

{

fprintf(stdout, "num = %u, id = %u, name = %s, subject = %s, score = %u\n", p->num, p->data.id, p->data.name, p->data.subject, p->data.score);

p = p->next;

}

}

8、双链表的翻转（逆序、倒序）

void dlist_reverse(DList list)

{

if(dlist_is_empty(list))

{

fprintf(stdout, "The list is empty.No reverse.\n");

return ;

}

DList prev, current, pnext;

current = list->next;//跳过头节点，当前节点为第一个节点

pnext = current->next;//当前节点的下一个节点

current->next = NULL;//当前节点断开后续连接，作为尾节点

while(pnext)

{

prev = pnext->next;//将当前节点的下一个节点作为当前节点的前一个节点

pnext->next = current;//当前节点的前一个节点的指针域指向当前节点

current = pnext;//将下一个节点作为当前节点

pnext = prev;//前一个节点作为下一个节点

}

list->next = current;//头结点指针域指向当前节点，完成逆序

//重新给逆序后的各节点赋值新的序号

int i = 1;

while(current)

{

current->num = i++;

current = current->next;

}

}

代码见附件。

本文出自 “生命不息，奋斗不止” 博客，转载请与作者联系！