链表基本操作及代码

这里介绍链表的基本操作及其C语言实现代码

一、单向链表

1、创建

一般传入链表长度，返回头节点

List *CreateList(int n)

{

List *head = NULL;//头节点

List *tail = NULL;//尾节点

List *p = NULL;//临时接入节点

printf("create a list with n length!\n");

while(n-- > 0)

{

p = (List *)malloc(sizeof(List));

if(p == NULL)

{

exit(-1);

}

printf("please input data of list\n");

scanf("%d", &p->data);

p->next = NULL;//插入一个节点，next=NULL,方便理解

if(head == NULL)

{

head = p;//头节点

tail = head;//

}

else

{

tail->next = p;//别被搞糊涂了，不就为了与上以节点连接么

tail = p;//本质就是让新节点变成尾节点，并与上以节点连接

}

}

return head;

}

2、释放节点

注意释放次序

void Free(List *head)

{

List *p = NULL;

while(head->next != NULL)

{

p = head->next;//记得保存下一个节点

free(head);

head = p;

}

free(head);

head = NULL;

}

3、链表遍历

void ListOut(List *head)

{

if(head == NULL)

{

printf("empity list !\n");

return ;

}

while(head->next != NULL)

{

printf("%d ", head->data);

head = head->next;

}

printf("%d\n", head->data);

}

4、插入节点

这里注意一点，如果要输出头节点，有两种方式：1、通过return 返回，2、传入头结点地址即&head

这里最容易出错！！还有注意节点指向的位置，尤其头节点！！

void Insert(List **head, int pos)

{

List *p = NULL;

List *q = NULL;

List *newl = NULL;

int val;

int i = 0;

if(pos < 0)

{

printf("your position is must >= 0!\n");

return;

}

printf("please input the data of new node!\n");

scanf("%d", &val);

newl = (List *)malloc(sizeof(List));

newl->data = val;

newl->next = NULL;

p = *head;

while(i != pos && NULL !=p->next)

{

q = p;

p = p->next;

i++;

}

if(i == pos)

{

if(i == 0)

{

q = *head;

*head = new1;

new1->next = q;

return;

}

else

{

q->next = newl;

newl->next = p;

return;

}

else if(i+1 == pos)

{

p->next = new1;

new1->next = NULL;

return ;

}

else

{

printf("your position is too big !\n ");

return ;

}

}

5、链表逆序

void reverse(List **head)

{

//注意若逆序输出的表头仍然用传入表头，必须对传入参数取地址&head

//如同int 一样，只能通过改变表头（指针）地址来改变其指向，不然List *head只是临时变量不会改变原参数

List *p = NULL;

List *temp = NULL;//临时节点

p = *head;

*head = NULL;//逆序第一个节点->next = NULL,这里head不再起左右，只是当作一个临时变量并最后保存新head而已。

while(p->next != NULL)

{

temp = p;

p = p->next;//先保存，不然后面就变了

temp->next = *head;

*head = temp;

}

p->next = *head;

*head = p;

}

二、双向链表

typedef struct List

{

int data;

struct List *prev;

struct List *next;

}List;

1、创建

List *CreateDlist(int n)

{

List *head = NULL;

List *p = NULL;

List *tail = NULL;

while(n--)

{

p = (List *)malloc(sizeof(List));

if(NULL == p)

{

printf("no memory for p!\n");

exit(-1);

}

printf("please input data of nodes\n");

scanf("%d", &p->data);

if(NULL == head)

{

tail = p;

head = tail;

tail->prev = head;

head->next = tail;

}

else

{

tail->next = p;

p->prev = tail;

p->next = p;

tail = p;

}

}

return head;

}

2、遍历

void Display(List *head)

{

List *p = head;

while(p->next != p)

{

printf("%d ", p->data);

p = p->next;

}

printf("%d\n", p->data);

}

3、插入

void Insert(List **head, int pos)

{

List *p = *head;

List *temp = NULL;

List *q = NULL;

int i = 0;

q = (List *)malloc(sizeof(List));

if(NULL == q)

{

printf("no memory for node!\n");

exit(-1);

}

printf("please input the data of new node!\n");

scanf("%d", &q->data);

while(p->next != p)

{

if(i == pos)

{

if(p == *head)//header

{

temp = *head;

*head = q;

(*head)->next = temp;

(*head)->prev = *head;

temp->prev = *head;

i++;

break;

}

else

{

temp = p->prev;

temp->next = q;

q->prev = temp;

q->next = p;

p->prev = q;

i++;//for the last node insert

break;

}

}

else

{

p = p->next;

i++;

}

}

if((i == pos) && ( p->next == p))//tail

{

temp = p->prev;

temp->next = q;

q->prev = temp;

q->next = p;

p->prev = q;

}

}

3、释放节点

void Free(List *head)

{

List *p = NULL;

while(head->next != head)

{

p = head->next;

free(head);

head = p;

}

free(head);

printf("free nodes sucessfully!\n");

}

4、逆序输出

void Reverse(List **head)

{

List *p = *head;

List *temp = NULL;

while(p->next != p)//这比单向列表简单多了

{

temp = p->next;

p->next = p->prev;

p->prev->prev = p;

p = temp;

}

p->next = p->prev;//tail

p->prev->prev = p;

p->prev = p;

*head = p;

}

int main()

{

int n;

List *head;

int pos;

printf("length of list!\n");

scanf("%d", &n);

head = CreateDlist(n);

Display(head);

/*

while(1)

{

printf("please input the position) of node you want to insert!\n");

scanf("%d", &pos);

Insert(&head, pos);

Display(head);

}

*/

Reverse(&head);

Display(head);

Free(head);

return 0;

}