双向链表

双向链表的创建、插入、删除、销毁：

main.c

#include "../include/link.h"


int menu(void)
{
    int op = 0;

    printf("1----------insert_link\n");
    printf("2----------del_link\n");
    printf("3----------show_link\n");
    printf("-1----------exit\n");
    scanf("%d",&op);
    return op;
}


int main(void)
{
    Link *p = NULL;
    p = empty_link();
    //printf("OK\n");
    
    int pos = 0;
    int op = 0;
    data_type item = 0;
    int ret = 0;
    
    system("clear"); //在C中调用Linux命令
    
    while(1)
    {
        op = menu();
        if(-1 == op)
        break;    
        switch(op)    
        {
            case 1:
                //insert
                printf("请输入您要插入的位置和数据\n");
                scanf("%d %d",&pos,&item);
                ret = insert_link(p,pos,item);
                if(ret != OK)
                {
                    printf("插入失败\n");
                    if(ret == ERROR)
                    {
                        printf("插入位置有误\n");
                    }
                }
                else
                {
                    printf("插入成功\n");
                }
                break;    
            
            case 2:
                //delete
                printf("请输入您要删除位置\n");
                scanf("%d",&pos);
                ret = del_link(p,pos,&item);
                if(ret==OK)
                {
                    printf("删除成功,数据为%d\n",item);    
                }            
                break;
            case 3:
                //show    
                show_link(p);
                break;


            default:
                printf("error");
        }    
    }

    destruction_link(&p);
    return 0;    
}

link.c

#include "../include/link.h"



//创建空链表
Link *empty_link(void)
{
    //创建空链表
    Link *pLink = NULL;
    pLink = (Link *)malloc(sizeof(Link));
    if(NULL == pLink)
    {
        perror("malloc error");
    }
    memset(pLink,'\0',sizeof(Link));
    
    //创建空节点
    pLink->pHead = (Node *)malloc(sizeof(Node));
    if(NULL == pLink)
    {
        perror("malloc error");
        return NULL;
    }
    memset(pLink->pHead,'\0',sizeof(Node));
    
    //count赋初值
    pLink->count = 0;
    
    return pLink;
}

//插入节点
int insert_link(Link *pLink,int pos,data_type item)
{
    //创建新节点
    Node *pNew = NULL;
    pNew = (Node *)malloc(sizeof(Node));
    if(NULL == pNew)
    {
        perror("malloc error");
        return ERROR;
    }
    Node *pTmp = NULL;
    pTmp = pLink->pHead;
    
    switch(pos)
    {
        case HEAD:
            pNew->next = pLink->pHead->next;
            pLink->pHead->next = pNew;
            pNew->per = pLink->pHead;
            pNew->data = item; 
            break;
        case TAIL:

            while(pTmp->next != NULL)
            {        
                pTmp = pTmp->next;
            }
            pTmp->next = pNew;
            pNew->per = pTmp;
            pNew->data = item; 
            break;
        default:
            while(--pos)
            {        
                pTmp = pTmp->next;
            }
            pNew->per = pTmp;
            pNew->next = pTmp->next;
            pTmp->next->per = pNew;
            pTmp->next = pNew;
            
            pNew->data = item; 
            break;
    }
    pLink->count++;
    return OK;
}

//删除节点
int del_link(Link *pLink,int pos,data_type *data)
{
    Node *pTmp = NULL;
    pTmp = pLink->pHead;
    switch(pos)
    {
        case HEAD:
            pTmp = pTmp->next;
            pLink->pHead->next = pTmp->next;
            pTmp->next->per = pLink->pHead;
            *data = pTmp->data;
            free(pTmp);
            pTmp = NULL;    
            break;
        case TAIL:
            while(pTmp->next != NULL)
            {
                pTmp = pTmp->next;
            }
            pTmp->per->next = NULL;
            *data = pTmp->data;
            free(pTmp);
            pTmp = NULL;    
        default:
            while(pos--)
            {
                pTmp = pTmp->next;
            }
            pTmp->per->next = pTmp->next;
            pTmp->next->per = pTmp->per;
            *data = pTmp->data;
            free(pTmp);
            pTmp = NULL;    
            break;
    }
    pLink->count--;
    return OK;
}

//输出链表
int show_link(Link *pLink)
{
    Node *pTmp = NULL;
    pTmp = pLink->pHead;
    while(pTmp->next != NULL)
    {
        pTmp = pTmp->next;
        printf("%d ",pTmp->data);
    }
    printf("\n");
    return OK;
}

//销毁链表
int destruction_link(Link **ppLink)
{
    Node *pTmp = NULL;
    while((*ppLink)->pHead->next != NULL)
    {
        pTmp = (*ppLink)->pHead->next;
        (*ppLink)->pHead->next = pTmp->next;
        free(pTmp);
        pTmp = NULL;
    }
    free((*ppLink)->pHead);
    (*ppLink)->pHead = NULL;
    free(*ppLink);
    *ppLink = NULL;
    return OK;
}

link.h

#ifndef _LINK_H
#define _LINK_H

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

#define N 10

typedef int data_type;

//节点
typedef struct node
{
    struct node *per;
    struct node *next;
    data_type data;    
}Node;

//链表
typedef struct link
{
    Node *pHead;
    Node *pTail;
    int count;
}Link;

//设置返回值
enum error
{
    ERROR = -1,
    OK
};

//头尾标志
enum pos
{
    TAIL = -1,
    HEAD
};

//创建空链表
Link *empty_link(void);

//插入节点
int insert_link(Link *pLink,int pos,data_type item);

//删除节点
int del_link(Link *pLink,int pos,data_type *data);

//输出链表
int show_link(Link *pLink);

//销毁链表
int destruction_link(Link **ppLink);


#endif