C语言单链表

喜欢ヅ旅行 2022-06-10 06:11 211阅读 0赞

**不多说，直接上马，一个水果实例：**

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    //这是跳过警告，在vs编译器中使用，需加上词句
    #pragma warning(disable:4996)
    #define WHILE_ONE 1
    
    struct fruit
    {
        char name[20];
        double price;
    };
    struct fruitLink
    {
        struct fruit data;//值域
        struct fruitLink *next;//指针域
    };

**下为函数声明**

//1.0创建新节点
    struct fruitLink * CreateNewNode(struct fruit data);
    //2.0判断头节点是不是NULL，是NULL-0,非NULL-1
    int isNullHeadNode(struct fruitLink *head);
    //3.0后插法
    void Insert_After(struct fruitLink *head, struct fruit data);
    //4.0打印链表数据
    void Print_Link(struct fruitLink * head);
    //5.0根据水果姓名查找
    struct fruitLink *Find_Name(struct fruitLink * head, char * name);
    //6.0获取新增的水果，然后调用后插法
    void Add_Fruit(struct fruitLink * head);
    //7.0菜单
    void Printf_Menu();
    //8.0获取删除水果名称
    void Del_Fruit(struct fruitLink *head);
    //9.0删除水果
    void Del_Name(struct fruitLink * head, char* name);
    //10.0按水果价格降序排序
    void Sort_Fruit_Price(struct fruitLink *head);
    //11.0修改水果价格
    void Modify_Fruit_Price(struct fruitLink *head);
    //12.0保存到txt
    void Save(struct fruitLink* head);
    //13.0从txt中读取数据到链表
    void Load(struct fruitLink* head);
    //14.0销毁链表
    void FreeAll(struct fruitLink* head);

**主函数**

int main()
    {
        struct fruitLink * head = NULL;
        int choose = -1;
        //为头结点申请空间
        head = calloc(1, sizeof(struct fruitLink));
        head->next = NULL;
    
        while (WHILE_ONE)
        {
            //printf("****请选择****\n");
            Printf_Menu();
            scanf("%d", &choose);
    
            while (getchar() != '\n');
            switch (choose)
            {
            case 1://添加水果
                Add_Fruit(head);
                break;
            case 2://删除水果
                Del_Fruit(head);
                break;
            case 3://按水果价格排序
                Sort_Fruit_Price(head);
                break;
            case 4://修改水果价格
                Modify_Fruit_Price(head);
                break;
            case 5://打印
                Print_Link(head);
                break;
            case 6://保存
                Save(head);
                break;
            case 7://加载
                Load(head);
                break;
            case 0://退出         
                Save(head);
                FreeAll(head);
                return 0;
            default:
                printf("选择错误!!\n");
                break;
            }
        }
    
        return 0;
    }

**菜单**

void Printf_Menu()
    {
        printf(" ##################\n");
        printf(" 1.添加水果\n");
        printf(" 2.删除水果-(名字)\n");
        printf(" 3.排序水果-(价格)\n");
        printf(" 4.修改水果-(价格)\n");
        printf(" 5.打印水果\n");
        printf(" 6.保存\n");
        printf(" 7.加载\n");
        printf(" 0.退出\n");
        printf(" ##################\n");
    }

**修改水果价格，通过水果名**

void Modify_Fruit_Price(struct fruitLink *head)
    {
        char name[20] = "";
        double price = 0;
        printf("请输入要删除水果名!\n");
        scanf("%s", &name);
        struct fruitLink * p = Find_Name(head, name);
        if (NULL == p)
        {
            printf("未找到该水果名称，请检查输入的正确性！\n");
            return;
        }
        printf("请输入新的价格!\n");
        scanf("%lf", &price);
        if (price <= 0)
        {
            printf("你他妈要赔了。。。\n");
            return;
        }
        p->next->data.price = price;
        printf("修改%s水果价格成功！\n", name);
    
    }

**按水果价格降序排列，冒泡**

void Sort_Fruit_Price(struct fruitLink *head)
    {
        if (0 == isNullHeadNode(head)) return;
        head = head->next;
    
        struct fruitLink* t = head;
        int lengh = 0;
    
        while (head != NULL)
        {
            lengh++;
            head = head->next;
        }
        for (int i = 0; i < lengh; i++)
        {
            head = t;
            for (int j = 0; j < lengh - i - 1; j++)
            {
                if (head->data.price > head->next->data.price)
                {
                    struct fruit temp = head->data;
                    head->data = head->next->data;
                    head->next->data = temp;
                }
                head = head->next;
            }
        }
        printf("排序成功\n");
    }

**删除水果**

void Del_Fruit(struct fruitLink *head)
    {
        char name[20] = "";
        printf("请输入要删除的水果名称!\n");
        scanf("%s", &name);
        //验证输入水果名的正确性
        if (NULL == Find_Name(head, name))
        {
            printf("未找到该水果名称，请检查输入的正确性！\n");
            return;
        }
        Del_Name(head, name);
    }
    //通过水果名删除
    void Del_Name(struct fruitLink * head, char* name)
    {
        if (0 == isNullHeadNode(head)) return;
        //要删除节点的前一个节点
        struct fruitLink* pre = Find_Name(head, name);
        //要删除的节点
        struct fruitLink* del = pre->next;
        pre->next = del->next;
        free(del);
        printf("删除%s水果成功！\n", name);
    }

**创建一个新节点，新节点的下一个节点指向null，前节点无指向**

struct fruitLink * CreateNewNode(struct fruit data)
    {
        //为新节点申请堆空间
        struct fruitLink * newNode = calloc(1, sizeof(struct fruitLink));
        newNode->data = data;
        newNode->next = NULL;
        return newNode;
    }

**判断头节点是不是为空**

int isNullHeadNode(struct fruitLink *head)
    {
        if (NULL == head)
        {
            printf("头结点为空\n");
            return 0;
        }
        return 1;
    }

**打印链表（循环）**

void Print_Link(struct fruitLink * head)
    {
        struct fruitLink * head_t = head;
        if (0 == isNullHeadNode(head_t)) return;
        head_t = head_t->next;
        printf("*************打印开始************\n");
        printf("水果名\t水果价格\n");
        while (head_t!=NULL)
        {
            printf("%s\t%lf\n", head_t->data.name, head_t->data.price);
            head_t = head_t->next;
        }
        printf("*************打印结束************\n");
    }

**按水果名查找，返回前一个节点()**

struct fruitLink *Find_Name(struct fruitLink * head, char * name)
    {
        if (0 == isNullHeadNode(head)) return NULL;
        struct fruitLink * pre = head;
        struct fruitLink * next = pre->next;
        while (NULL != next)
        {
            if (0 == strcmp(next->data.name, name)) {
                return pre;
            }
            pre = next;
            next = next->next;
        }
        printf("没有这个水果\n");
        return NULL;
    }

**添加水果**

void Add_Fruit(struct fruitLink * head)
    {
        struct fruit newFruit;
        printf("请输入新的水果名称\n");
        scanf("%s", &newFruit.name);
        if (NULL == Find_Name(head, newFruit.name))
        {
            printf("请输入水果价格\n");
            scanf("%lf", &newFruit.price);
            if (newFruit.price <= 0) {
                printf("价格是负的了要赔了，你个傻逼！\n");
                return;
            }
            Insert_After(head, newFruit);
            printf("成功添加新水果\n");
            return;
        }
        printf("应经有相同名字的水果了。。。\n");
        return;
    }
    
    //向最后一个节点后插入新节点，并赋值数据
    void Insert_After(struct fruitLink *head, struct fruit data)
    {
        struct fruitLink * head_t = head;
        if (0 == isNullHeadNode(head_t))
            return;
    
        //找到最后一个节点
        while (head_t->next != NULL)
        {
            head_t = head_t->next;
        }
        //最后一个节点指向新节点
        head_t->next = CreateNewNode(data);
    }

**释放链表**

void FreeAll(struct fruitLink* head)
    {
        if(0==isNullHeadNode(head) ) return;
    
        struct fruitLink* temp ;
        head=head->next;
        while(head!=NULL)
        {
            temp=head->next;
            free(head);
            head=temp;
        }
        printf("链表已销毁\n");
    }

**保存**

void Save(struct fruitLink* head)
    {
        if(0==isNullHeadNode(head)) return;
        FILE * fp=NULL;
        fp=fopen("fruit.txt","w+");
    
        head=head->next;
        while(head!=NULL)
        {
            //以二进制存储，会乱码
            //fwrite(&head->data,sizeof(struct fruit),1,fp);
            //按格式输入到流
            fprintf(fp,"%s\t%lf\r\n" ,head->data.name,head->data.price);
            head=head->next;
        }
        printf("保存成功！\n");
        fclose(fp);
    }

**加载数据**

void Load(struct fruitLink* head)
    {
        int flag=0;
        if(0==isNullHeadNode(head)) return;
        FILE * fp=NULL;
        fp=fopen("fruit.txt","r+");
        if(NULL==fp) 
        {
            printf("无数据\n");
            system("touch fruit.txt");
            return;
        }
        //方法一:
        while(!feof(fp))
        {
            struct fruit stu;       
            fscanf(fp,"%s\t%lf\r\n",&stu.name,&stu.price);
            Insert_After(head,stu);
        }
        //方法二:
        //while(1)
        //{ 
        // struct fruit stu; 
        // flag=fread(&stu,sizeof(struct fruit),1,fp);
    
        // if(flag<1) break;
        // Insert_After(head,stu);
        //}
        printf("加载成功\n");
        fclose(fp);
    }

呵呵，我也是个菜鸟，有错误还请留言，以便更正。  
有更好的方法还请留言探讨，程序员快乐！！！