双向链表的简单操作

双链表的结构体

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

双链表的创建

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;
}

双链表的遍历

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;
    }   
}

双链表的插入

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;    
}

双链表的删除

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;
}

以下是所有的操作

#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;
}