双向链表的简单操作

typedef struct Linklist{
int data;
struct Linklist *prior,*next;
}node;

node *create(){
node *head,*p1,*p2;
head=(node*)malloc(sizeof(node));
head->next=NULL;
p1=(node*)malloc(sizeof(node));
printf("please input data:");
scanf("%d",&p1->data);
while(p1->data){
len++;
if(len==1){
head->next=p1;
p1->prior=head;
p2=p1;
}
else{
p2->next=p1;
p1->prior=p2;
p2=p1;
}
p1=(node*)malloc(sizeof(node));
printf("please input data:");
scanf("%d",&p1->data);
}
free(p1);
p2->next=NULL;
return head;
}

void disp(node *head){
node *p=head->next;
node *q;
printf("len=%d\n",len);
while(p){
printf("%d ",p->data);
printf("%d ",p->prior->data); //上一个节点的值，检查prior是否连接正常
printf("\n");
p=p->next;
}
}

node *insert(node *head,node *newnode,int pos){
//插入的节点在首部
if(pos>len+1){
printf("pos error!\n");
exit(1);
}

if(pos==0){
printf("please input data:");
scanf("%d",&newnode->data);

newnode->next=head->next;
head->next->prior=newnode;
head->next=newnode;
newnode->prior=head;
}

//插入的节点在中间
else if((pos>0)&&(pos<len)){
printf("please input data:");
scanf("%d",&newnode->data);

node *p=head->next;
int cnt=1;
while(p){
if(pos==cnt){
node *q=p->next;

p->next=newnode;
newnode->prior=p;

newnode->next=q;
q->prior=newnode;
break;
}
p=p->next;
cnt++;
}
}

//插入节点在尾部
else if(pos==len){
node *p=head->next;
while(p->next!=NULL){
p=p->next;
}
printf("please input data:");
scanf("%d",&newnode->data);
p->next=newnode;
newnode->prior=p;
}
len++;
return head;
}

node *Delete(node *head,int pos){
if(pos > len){
printf("pos error!\n");
exit(1);
}

//int cnt=1;
if(pos==1){
node *q=head->next->next;

head->next=q;
q->prior=head;
}
else if((pos>1)&&(pos<len)){
int cnt=2;
node *p=head->next;
while(p){
if(pos==cnt){
node *q= p->next->next;

p->next=q;
q->prior=p;
break;
}
}
}
else if(pos==len){

node *p=head->next;
while(p->next->next){
p=p->next;
}
p->next=NULL;
}
len--;
return head;
}

#include<stdio.h>
#include<stdlib.h>
int len=0;
//双向链表的定义
typedef struct Linklist{
int data;
struct Linklist *prior,*next;
}node;

//双向链表的创建
node *create(){
node *head,*p1,*p2;
head=(node*)malloc(sizeof(node));
head->next=NULL;
p1=(node*)malloc(sizeof(node));
printf("please input data:");
scanf("%d",&p1->data);
while(p1->data){
len++;
if(len==1){
head->next=p1;
p1->prior=head;
p2=p1;
}
else{
p2->next=p1;
p1->prior=p2;
p2=p1;
}
p1=(node*)malloc(sizeof(node));
printf("please input data:");
scanf("%d",&p1->data);
}
free(p1);
p2->next=NULL;
return head;
}

void disp(node *head){
node *p=head->next;
node *q;
printf("len=%d\n",len);
while(p){
printf("%d ",p->data);
printf("%d ",p->prior->data); //上一个节点的值，检查prior是否连接正常
printf("\n");
p=p->next;
}
}
//节点的插入
node *insert(node *head,node *newnode,int pos){
//插入的节点在首部
if(pos>len+1){
printf("pos error!\n");
exit(1);
}

if(pos==0){
printf("please input data:");
scanf("%d",&newnode->data);

newnode->next=head->next;
head->next->prior=newnode;
head->next=newnode;
newnode->prior=head;
}

//插入的节点在中间
else if((pos>0)&&(pos<len)){
printf("please input data:");
scanf("%d",&newnode->data);

node *p=head->next;
int cnt=1;
while(p){
if(pos==cnt){
node *q=p->next;

p->next=newnode;
newnode->prior=p;

newnode->next=q;
q->prior=newnode;
break;
}
p=p->next;
cnt++;
}
}

//插入节点在尾部
else if(pos==len){
node *p=head->next;
while(p->next!=NULL){
p=p->next;
}
printf("please input data:");
scanf("%d",&newnode->data);
p->next=newnode;
newnode->prior=p;
}
len++;
return head;
}
//节点的删除
node *Delete(node *head,int pos){
if(pos > len){
printf("pos error!\n");
exit(1);
}

//int cnt=1;
if(pos==1){
node *q=head->next->next;

head->next=q;
q->prior=head;
}
else if((pos>1)&&(pos<len)){
int cnt=2;
node *p=head->next;
while(p){
if(pos==cnt){
node *q= p->next->next;

p->next=q;
q->prior=p;
break;
}
}
}
else if(pos==len){

node *p=head->next;
while(p->next->next){
p=p->next;
}
p->next=NULL;
}
len--;
return head;
}

int main(){
node *head=create();
disp(head);
node *newnode=(node*)malloc(sizeof(node));

//Delete(head,1);
insert(head,newnode,0);

disp(head);
return 0;
}