#include<stdio.h>

#include"stdlib.h" 

struct student

{

int data;

struct student *pnext;

};

struct students

{

struct students *prev;

int data;

struct students *pnext;

};

struct student *create(int dat); //单链表创造一个节点。

struct students *shuangcreate(int dat); //双链表创造一个节点。

void insert_head(struct student* pH,struct student* news);//单链表头插入

void insert_head_shuang(struct students* pH,struct students* news);//双链表头插入

void insert_tail_shuang(struct students* pH,struct students* news);//尾插入

int main()

{

struct student *ph=create();

struct students *phs=shuangcreate();

insert_head(ph,create());

insert_head(ph,create());

insert_head_shuang(phs,shuangcreate());

insert_head_shuang(phs,shuangcreate());

insert_head_shuang(phs,shuangcreate());

/*

insert_tail_shuang(phs,shuangcreate(1));  //尾插入

insert_tail_shuang(phs,shuangcreate(2));

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

printf("%d.\n",ph->pnext->data);

printf("%d.\n",ph->pnext->pnext->data);

*/

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

printf("%d.\n",phs->pnext->data);

printf("%d.\n",phs->pnext->pnext->data);

printf("%d.\n",phs->pnext->pnext->pnext->data);

return ;

}

struct student *create(int dat) //单链表创造一个节点。

{

struct student *p=(struct student*)malloc(sizeof(struct student));

if(NULL==p)

{

return NULL;

printf("节点分配失败");

}

p->data=dat;

p->pnext=NULL;

return p;

}

struct students *shuangcreate(int dat) //双链表创造一个节点。

{

struct students *p=(struct students*)malloc(sizeof(struct students));

if(NULL==p)

{

return NULL;

printf("双链表节点分配失败");

}

p->data=dat;

p->pnext=NULL;

p->prev=NULL;

return p;

}

void insert_head(struct student* pH,struct student* news)

{

news->pnext=pH->pnext;

pH->pnext=news;

}

void insert_tail_shuang(struct students* pH,struct students* news)   //双链表的尾插入

{

struct students* ph=pH;

while(NULL!=ph->pnext)

{

ph=ph->pnext;

printf("a\n");

}

ph->pnext=news;

news->prev=ph;

}

//画出双链表的节点链接情况

void insert_head_shuang(struct students* pH,struct students* news)  //双链表的头插入

{

struct students* p=pH;

news->pnext=p->pnext;

if(p->pnext!=NULL)           //考虑到只有一个头结点的情况。这里很重要 当第一次的时候p->pnext=NULL;

p->pnext->prev=news;

p->pnext=news;

news->prev=p;

}