双向链表简单实现

/*********************************************************************************
*      Copyright:  (C) 2015 songyong<handy_skyoutlook.com>
*                  All rights reserved.
*
*       Filename:  double_link.c
*    Description:  This file
*
*        Version:  1.0.0(2015年09月20日)
*         Author:  sky <handy_sky@outlook.com>
*      ChangeLog:  1, Release initial version on "2015年09月20日 16时30分20秒"
*
********************************************************************************/
#include<stdio.h>
#include<stdlib.h>

#define LINK_LEN sizeof(struct double_link)

typedef struct double_link
{
int data;
struct double_link *pre;
struct double_link *next;
}db_link;

void print(db_link *head);
db_link *insert_link_tail(db_link *head);
db_link *create_link();
db_link *delete_link(db_link *head);
int i = 0;
/********************************************************************************
*  Description:
*   Input Args:
*  Output Args:
* Return Value:
********************************************************************************/
int main (int argc, char **argv)
{
db_link *phead = NULL;

phead = create_link();
phead = insert_link_tail(phead);
print(phead);
phead = delete_link(phead);
print(phead);
return 0;
} /* ----- End of main() ----- */

db_link *create_link()
{
db_link *head, *p, *s;
head = (db_link *)malloc(LINK_LEN);
p = head;
int n = 0;

printf("please input data about how many link to create:");
scanf("%d",&n);

if(NULL == head)
{
printf("malloc fail\n");
return 0;
}
head->pre = NULL;
head->next = NULL;

for(; n > 0; n--)
{
i++;
printf("please input a link\n");
s = (db_link *)malloc(LINK_LEN);
scanf("%d",&s->data);
p->next = s;
s->pre = p;
p = s;
}
p->next = NULL;
return head;
}

db_link *insert_link_tail(db_link *head)
{
db_link *p =head;
db_link *s = NULL;
int n = 0;

print(p);
printf("please choise insert address(0 - %d)\n",i);//0为第一个节点的为位置，1为第二个节点的位置
scanf("%d",&n);

while(n > i || n < 0)
{
printf("error:please choise 0 - 5\n");
exit(0);
}

for(; n > 0; n--)
p = p->next;

printf("please input a new link to inset:\n");
s = (db_link *)malloc(sizeof(LINK_LEN));
scanf("%d",&s->data);

if(NULL == p->next)
{
p->next = s;
s->pre =p;
s->next = NULL;
}
else
{
s->pre = p;
s->next = p->next;
p->next->pre = s;
p->next = s;
}
i++;
return head;
}

void print(db_link *head)
{
db_link *temp = head->next;

for(;temp != NULL;temp = temp->next)
printf(" %d ",temp->data);
printf("\n");
}

db_link *delete_link(db_link *head)
{
db_link *p =head;
int n;

printf("Now,we have %d links.\n",i);
printf("please choice a link to delete:\n");
scanf("%d",&n);

if(n <= 0 || n >i )
{
printf("please input data 0 < n <= %d\n",i);//保证头结点不被删除
exit(0);
}
for(;n > 0; n--)
p = p->next;

if(p->next)
{
p->next->pre = p->pre;
p->pre->next = p->next;
}
else
p->pre->next = NULL;

free(p);
return head;
}

void reverse_link(db_link *head)
{
db_link *p = head;

for(;NULL != p->next; p = p->next);//找到末节点;
printf("reverse link:\n");
while(p->pre)
{
printf(" %d ",p->data);
p = p->pre;
}
printf("\n");
}