双向链表

代码 1 :

#include <stdio.h>
#include <stdlib.h>

typedef int data_t;

typedef struct node{
    data_t data;
    struct node * front;
    struct node * next;
}duolist_t;

//创建
duolist_t* create_duolist()
{
    duolist_t* list=malloc(sizeof(duolist_t));

    list->front=NULL; //头结点指向前方的指针

    list->next=malloc(sizeof(duolist_t));//头结点指向后面的指针

    list->next->front=list;//尾节点指向前面的指针

    list->next->next=NULL;//尾节点指向后面的指针

    return list;
}

//判空
int isempty(duolist_t* list)
{
    if(list==NULL)
        return 0;

    return list->next->next==NULL;

}

//增
int insert_duolist(duolist_t* list,data_t data)
{
    if(list==NULL)
        return -1;


    duolist_t* newnode=malloc(sizeof(duolist_t));

    newnode->data=data;


    newnode->front=list;

    newnode->next=list->next;

    newnode->front->next=newnode;

    newnode->next->front=newnode;

    return 0;
}

//删
int delete_duolist(duolist_t* list)
{
    if(list==NULL||isempty(list))
        return -1;

    duolist_t* temp=list->next;

    temp->front->next=temp->next;

    temp->next->front=temp->front;

    free(temp);

    return 0;
}

//查   返回谁的地址？
duolist_t* locate_duolist(duolist_t* list,data_t data)
{
    if(list==NULL||isempty(list))
        return NULL;

    while(list->next->next!=NULL)
    {
        if(list->next->data==data)
            return list->next;

        list=list->next;
    }

    return NULL;
}

//改
int change_duolist(duolist_t* list,data_t data)
{
    if(list==NULL)
        return -1;

    list->data=data;

    return 0;
}

//打印
int print_duolist(duolist_t* list)
{
    if(list==NULL||isempty(list))
        return -1;

    while(list->next->next!=NULL)
    {
        printf("%3d ",list->next->data);

        list=list->next;
    }
    printf("\n");

    return 0;
}

//逆打印
int reprint_duolist(duolist_t* list)
{
    if(list==NULL||isempty(list))
        return -1;


    while(list->next->next!=NULL)
    {
        list=list->next;

    }
    list=list->next;

    while(list->front->front!=NULL)
    {
        printf("%3d ",list->front->data);

        list=list->front;
    }
    printf("\n");

    return 0;
}

//长度
int length_duolist(duolist_t* list)
{
    if(list==NULL||isempty(list))
        return 0;

    int sum=0;
    while(list->next->next!=NULL)
    {
        sum++;

        list=list->next;
    }

    return sum;

}

//清空
int clear_duolist(duolist_t* list)
{
    if(list==NULL||isempty(list))
        return -1;

    while(list->next->next!=NULL)//length_duolist(list)
    {
        delete_duolist(list);

    }

    return 0;
}

//销毁
int destroy_duolist(duolist_t* list)
{
    if(list==NULL)
        return -1;

    if(!isempty(list))
        clear_duolist(list);

    free(list->next);

    free(list);

    return 0;
}

int main(int argc, const char *argv[])
{
    duolist_t* list=create_duolist();

    int i;

    for(i=1;i<=15;i++)
    {
        insert_duolist(list,i*2);

        print_duolist(list);
    }

    change_duolist(locate_duolist(list,20),250);
    print_duolist(list);

    insert_duolist(locate_duolist(list,250)->front,20);

    print_duolist(list);

    delete_duolist(locate_duolist(list,250)->front);

    print_duolist(list);

    reprint_duolist(list);

    printf("length_duolist:%d\n",length_duolist(list));

    clear_duolist(list);

    printf("length_duolist:%d\n",length_duolist(list));

    destroy_duolist(list);

    list=NULL;

    return 0;
}