学生成绩管理系统链表实现

我就是我 2022-07-16 13:38 256阅读 0赞

2016年7月11日18:02:51 链表的相关术语: 头结点:1.为什么需要头结点? 为了方便对链表的操作,因而需要头结点;
               2.头结点是什么?
                链表的第一个节点,首节点前面那节点,但该节点不保存有效数据;
        首节点:首节点是链表中第一个保存有效数据的节点;
        尾节点:尾节点是链表中最后一个保存有效数据的节点,该节点的指针域为空;
        头指针:保存头结点地址的指针变量为头指针;
        确定一个链表至少需要那几个参数?(或者说:如果要用一个函数来处理一个链表,那么该函数至少需要接受链表那几个参数) 确定一个链表只需要一个参数:头指针 这是因为,由链表的头指针可以找到链表的头结点,根据头结点的指针域可以找到链表的首节点,一直往后找知道找到链表的最后一个 节点,即尾节点,因此由头指针可以确定一个链表;
        链表的创建是动态的分配内存还是静态的分配内存?
        动态的分配内存:如果静态分配内存,那么一旦创建链表的函数执行完毕,那么系统就会自动释放静态内存空间, 而动态内存分配程序员可以通过编程来手动分配动态内存,也可以由程序员手动编程来释放动态内存.

#include<stdio.h>
    #include<malloc.h>
    #include<stdlib.h>
    
    //学生基本信息结构体
    typedef struct stu
    {
        long num;
        char name[10];
        float score;
    }STUDENT;
    
    //链表结构体
    typedef struct node
    {
        STUDENT data;
        struct node * pNext;
    }SNODE;
    
    //函数前置声明
    SNODE * createList(SNODE * pHead, int len);//尾插法
    SNODE * createList1(SNODE * pHead,int len);//头插法
    void traverseList(SNODE * pHead);//遍历链表
    void inputInfor(SNODE * pNew);//输入信息
    SNODE * insertNode(SNODE * pHead,int pos);//插入节点
    SNODE * deleteList(SNODE * pHead,int  pos);//删除节点
    SNODE * initList(SNODE * pHead);//初始化链表
    SNODE * locateElem(SNODE * pHead,long  num);//根据内容查找
    SNODE * getElem(SNODE * pHead,int pos);//根据位置查找
    int isEmpty(SNODE * pHead);//判断链表是否为空
    void destroyList(SNODE * pHead);//销毁链表
    void showMenu(void);//展示菜单
    
    //初始化链表
    SNODE * initList(SNODE * pHead)
    {
        pHead = (SNODE * )malloc(sizeof(SNODE));
        if(NULL == pHead)
        {
            printf("动态内存分配失败!\n");
            exit(-1);
        }
        pHead->pNext = NULL;
        pHead->data.num = 0;
        return pHead;
    }
    
    //判断链表是否为空,如果为空返回1,否则返回0
    int isEmpty(SNODE * pHead)
    {
        if(NULL == pHead->pNext)
            return 1;
        else
            return 0;
    }
    
    //求链表的长度,如果链表为空则返回0,非空则返回链表的长度
    int getLength(SNODE * pHead)
    {
        SNODE * p;
        int i = 0;
        p = pHead->pNext;
        /*if(1 == isEmpty(pHead)) return 0; else*/
        while(NULL != p)
        {
            p = p->pNext;
            i++;
        }
        return i;
    }
    
    
    void destroyList(SNODE * pHead)//销毁链表
    {
        SNODE * pFree,* pCur;
        pFree = pHead;
        while(pFree)
        {
            pCur = pFree->pNext;
            free(pFree);
            pFree = pCur;
        }
        return ;
    }
    
    //展示菜单
    void showMenu(void)
    {
        printf("___________________________________________\n");
        printf(" 欢迎使用学生成绩管理系统\n");
        printf("\t 【1】创建学生信息\n");
        printf("\t 【2】插入学生信息\n");
        printf("\t 【3】删除学生信息\n");
        printf("\t 【4】显示学生信息\n");
        printf("\t 【5】查找学生信息\n");
        printf("\t 【6】退出系统\n");
        printf("___________________________________________\n\n");
        return;
    }
    
    //动态的创建一个链表
    SNODE * createList(SNODE * pHead, int len)
    {
        SNODE * pNew;
        SNODE * pTail;
        pTail = pHead;
        int i;
        for( i = 0;i<len;i++)
        {
            pNew = (SNODE * )malloc(sizeof(SNODE));
            if(NULL == pNew)
            {
                printf("动态内存分配失败!\n");
                exit(-1);
            }
            inputInfor(pNew);
            pNew->pNext = NULL;
            pTail->pNext = pNew;
            pTail = pNew;
            pHead->data.num ++;
        }
        return pHead;
    }
    
    //单链表的创建之尾插法
    SNODE * createList1(SNODE * pHead,int len)
    {
        SNODE * pNew;
        int i;
        for(i = 0;i<len;i++)
        {
            pNew = (SNODE * )malloc(sizeof(SNODE));
            if(NULL == pNew)
            {
                printf("动态内存分配失败!\n");
                return NULL;
            }
            printf("请输入学生信息！\n");
            printf("学号=");
            scanf("%ld",&pNew->data.num);
            printf("姓名=");
            scanf("%s",pNew->data.name);
            printf("分数=");
            scanf("%f",&pNew->data.score);
            /*if( NULL == pHead->pNext) { pNew->pNext = NULL; pHead->pNext = pNew; } else { pNew->pNext = pHead->pNext; pHead->pNext = pNew; } */
            pNew->pNext = pHead->pNext;
            pHead->pNext = pNew;
        }
        return pHead;
    }
    
    //输入学生信息
    void inputInfor(SNODE * pNew)
    { 
        printf("请输入学生信息:\n");
        printf("学号=");
        scanf("%ld",&pNew->data.num);
        printf("姓名=");
        scanf("%s",pNew->data.name);
        printf("分数=");
        scanf("%f",&pNew->data.score);
        return;
    }
    
    
    //学生结点的插入
    SNODE * insertNode(SNODE * pHead,SNODE * cur,int pos)
    {
    
        SNODE * prev = pHead;
        int i;
        while(pos<1||pos>pHead->data.num+1)
        {
            return NULL;
        }
        for(i = 1;i<pos;i++)
        {
            prev = prev->pNext;
        }
        /* if(prev->pNext==NULL) { cur->pNext = NULL; prev->pNext = cur; pHead->data.num ++; } else { cur->pNext = prev ->pNext; prev->pNext = cur; pHead->data.num++; } */
        cur->pNext = prev ->pNext;
        prev->pNext = cur;
        pHead->data.num++;
        return pHead;
    }
    
    //学生结点的删除
    SNODE * deleteNode(SNODE * pHead,int  pos ,SNODE * pDelete)
    {
        SNODE * prev;
        SNODE * cur;
        int i;
        prev = pHead;
        if(NULL == pHead->pNext)
        {
            printf("链表为空，不能删除元素!\n");
            return NULL;
        }
        while(pos<1||pos>pHead->data.num)
        {
            return NULL;
        }
        for(i = 1;i<pos;i++)
        {
            prev = prev->pNext;
        }
        cur = prev->pNext;
        /*if(NULL == cur->pNext ) { prev->pNext = NULL; *pDelete = *cur; free(cur); pHead->data.num--; } else { prev->pNext = cur->pNext; *pDelete = *cur; free(cur); pHead->data.num--; } */
        prev->pNext = cur->pNext;
        *pDelete = *cur;
        free(cur);
        pHead->data.num--;
        return pHead;
    }
    
    //根据学生信息内容查找,查找成功返回元素指针,查找失败返回NULL;
    SNODE *  locateElem(SNODE * pHead,long  num)
    {
        SNODE * p;
        int pos = 0;
        p = pHead->pNext;
        /*if(NULL == pHead->pNext) { return 0; }*/
        while(NULL != p)
        {
            if(num == p->data.num)
            {
                return p;
            }
            p = p->pNext;
            pos++;
        }                                                                                                                                                                                      
        return NULL;
    }
    
    //根据学生信息位置查找,查找成功返回元素指针,查找失败返回NULL;
    SNODE *  getElem(SNODE * pHead,int pos)
    {
        SNODE * p;
        int i = 1;
        p = pHead->pNext;
        /*if(p == NULL) { return NULL; }*/
        while(NULL != p&&i<pos)
        {
            p = p->pNext;
            i++;
        }
        if(i == pos)
        {
            return p;
        }
        else
        {
            return NULL;
        }
    }
    
    //链表的遍历
    void traverseList(SNODE * pHead)
    {
        int i = 0;
        SNODE * p = NULL;
        p = pHead->pNext;
        printf(" 学号 姓名 分数 \n");
        if(NULL == p)
        {
            printf("链表为空!\n");
        }
        else
        {
            while(NULL != p)
            {
                printf("第%d个学生 ",i+1);
                printf("%-7ld%-7s%-6.2f\n",p->data.num,p->data.name,p->data.score);
                p = p->pNext;
                i++;
            }
        }
        return;
    }
    
    //主函数
    int main(void)
    {
        SNODE * pFound;
        SNODE * pInsertNode;
        SNODE pDeleteNode;
        SNODE * pHead = NULL;
        int len,pos,choice;
    
    
        pHead = initList(pHead);//初始化链表
        while(1)
        {
            showMenu();//展示链表的操作
            printf("请输入您的选择:");
            scanf("%d",&choice);
            system("cls");
            switch(choice)
            {
                case 1:printf("请输入原始班级中的人数:");
                       scanf("%d",&len);
                       pHead = createList(pHead,len);
                       system("cls");
                       printf("___________________________________________\n");
                       printf(" 创建的学生信息显示\n");
                       traverseList(pHead);
                       printf("___________________________________________\n\n");
                       break;
                case 2: pInsertNode = (SNODE * )malloc(sizeof(SNODE));
                        if(NULL == pInsertNode)
                        {
                            printf("动态内存分配失败!\n");
                            exit(-1);
                        }
                        inputInfor(pInsertNode);
                        while( NULL == insertNode(pHead,pInsertNode,pos))
                        {
                           printf("___________________________________________\n");
                           printf(" 插入前学生信息显示\n");
                           traverseList(pHead);
                           printf("___________________________________________\n\n");
                           printf("请输入需要插入学生信息的位置:"); 
                           scanf("%d",&pos);
                          system("cls");
                        }
                        printf("___________________________________\n");
                        printf(" 您需要插入学生显示\n");
                        printf(" 学号 姓名 分数 \n");
                        printf(" %-7ld%-7s%-6.2f\n",pInsertNode->data.num,pInsertNode->data.name,pInsertNode->data.score);
                        printf("___________________________________\n\n");
                        printf("___________________________________________\n");
                        printf(" 插入后学生信息显示\n");
                        traverseList(pHead);
                        printf("___________________________________________\n\n");
                        break;
                case 3: while( NULL ==deleteNode(pHead,pos ,&pDeleteNode))
                        {
                           printf("___________________________________________\n");
                           printf(" 删除前学生信息显示\n");
                           traverseList(pHead);
                           printf("___________________________________________\n\n");
                           printf(" 请输入需要删除学生信息的位置:");
                           scanf("%d",&pos);
                           system("cls");
                        }
                        printf("___________________________________\n");
                        printf(" 您需要删除学生显示\n");
                        printf(" 学号 姓名 分数 \n");
                        printf(" %-7ld%-7s%-6.2f\n",pDeleteNode.data.num,pDeleteNode.data.name,pDeleteNode.data.score);
                        printf("___________________________________________\n");
                        printf(" 删除后学生信息显示\n");
                        traverseList(pHead);
                        printf("___________________________________________\n\n");
                        break;
                case 4: system("cls");
                        printf("___________________________________________\n");
                        printf(" 该班级学生信息显示\n");
                        traverseList(pHead);
                        printf("___________________________________________\n\n");
                        break;
                case 5: pos = 0;
                        while(pos<1)
                        {
                            printf("请输入您所需要查找元素的学号:\n");
                            scanf("%d",&pos);
                            system("cls");
                        }
                        //pFound = getElem(pHead,pos);
                        pFound = locateElem(pHead,pos);
                        if(NULL == pFound)
                        {
                            printf("查找失败!\n");
                        }
                        else
                        {
                            printf("_______________________________________\n");
                            printf(" 学号 姓名 分数 \n");
                            printf("该学生的信息");
                            printf("%-7ld%-7s%-6.2f\n",pFound->data.num,pFound->data.name,pFound->data.score);
                            printf("_______________________________________\n\n");
                        }
                        break;
                case 6:exit(0);
                default:system("cls");
                        printf("您的操作有误!\n");
                        break;
            }
    
        }
        return 0;
    }