单链表的应用

成绩管理系统

期末考试终于考完了，可开始学习数据结构了，先准备写一个简陋的成绩管理系统来复习一下单链表的知识

需求分析

• 有基本的录入学生成绩功能
• 有基本的修改学生成绩功能
• 有基本的查找学生成绩功能
• 有基本的删除学生成绩功能
• 有基本的预览所有学生成绩功能

实现方式

• 录入学生成绩可以用头插法创建链表来实现
• 修改操作可以通过LocateElem函数找到需要修改的结点
• 查找功能通过LocateElem来实现
• 删除功能就是列表的删除操作
• 预览功能，直接用循环遍历输出就好了

功能的实现代码

/*状态码*/
#define ERROR 0
#define OK 1

typedef int Status;
/*ElemType的定义*/
typedef struct student
{
    char ID[20];
    char name[20];
    int ProgammingGrade;
    int MathGrade;
    int EnglishGrade;
    int sum;
    double average;
};
/*链表定义*/
typedef struct node
{
    struct student data;
    struct node *next;  
}Node;
typedef Node* LinkList;

/*输入的规范处理*/
/*字符串的输入，方便后续的程序编写*/
void StringInput(char *t,int len,char *notice)
{
    char input[100];
    do
    {
        printf("%s",notice);
        scanf("%s",input);
        if(strlen(input)>len)
            printf("exceed the max length!\n");
    }while(strlen(input)>len);
    strcpy(t,input);
}
/*整型的输入，方便后续的程序编写*/
int NumberInput(char *notice)
{
    int score = -1;
    while (score<0 || score>100)
    {
        printf("%s",notice);
        scanf("%d",&score);
        if(score<0 || score >100)
            printf("the score must in [0,100]!\n");
    }   
    return score; 
}

/*输出规范管理*/
void PrintData(Node *p)
{
    //输出单个结点的数据域
    printf("Student ID: %s\n",p->data.ID);
    printf("Name: %s\n",p->data.name);
    printf("C language score: %d\n",p->data.ProgammingGrade);
    printf("English score: %d\n",p->data.EnglishGrade);
    printf("Math score: %d\n",p->data.MathGrade);
    printf("The total score: %d\n",p->data.sum);
    printf("The average: %.2f\n",p->data.average);
    printf("\n\n");
}
Status PrintALLData(LinkList l)
{
    //输出整个链表的所有数据
    system("clean");
    Node *p;
    p = l->next;
    if(!p)//链表为空
    {
        printf("There aren't students' record.\n");
        return ERROR;
    }
    while (p)
    {
        PrintData(p);
        p = p->next;
    }
    return OK; 
}


Status Add(LinkList l)
{
    Node *p,*r;
    char ID[20],name[20];   
    r=l;
    while (1)
    {
        p = (Node*)malloc(sizeof(Node)); //为新结点申请空间
        if(!p)          //申请失败
        {
            printf("memory malloc failure!\n");
            return ERROR;
        }
        StringInput(ID,20,"Please input student ID:(press '0' return menu)");
        if(strcmp(ID,"0")==0)
            break;
        /*基础信息输入*/
        strcpy(p->data.ID,ID);
        StringInput(name,20,"Please input student name:");
        strcpy(p->data.name,name);
        p->data.ProgammingGrade = NumberInput("Please input C language Score[0,100]:");
        p->data.MathGrade = NumberInput("Please input Math Score[0,100]:");
        p->data.EnglishGrade = NumberInput("Please input English Score[0,100]:");
        p->data.sum = p->data.ProgammingGrade + p->data.MathGrade + p->data.EnglishGrade;
        p->data.average = (double)(p->data.sum) / 3;
        /*头插法建立链表*/
        p->next = NULL;
        r->next = p;
        r = p;
    }
    return OK;
}

/*
链表的LocateElem功能，稍作了些修改
对于这种查找分为两种方式
1.通过学生ID
2.通过学生name
*/
Node* LocateElem(LinkList l,char *find,char *way)
{
    Node *p;
    p = l->next;
    /*按姓名查询*/
    if(strcmp(way,"name")==0)               
    {
        while (p)
        {
            if(strcmp(p->data.name,find)==0)
                return p;
            p = p->next;
        }
    }
    /*按学号查询*/
    else if(strcmp(way,"ID")==0)
    {
        while (p)
        {
            if(strcmp(p->data.ID,find)==0)
                return p;
            p = p->next;
        }
    }
    return NULL;
}

/*查询功能*/
Status SearchStudent(LinkList l)
{
    system("clear");
    int choice;
    char SearchInput[10];
    Node *p;
    p = l->next;
    if(!p)
    {
        printf("There aren't students' record.\n");
        return ERROR;
    }
    /*查询功能的选择界面*/
    puts("1.search by ID");
    puts("2.search by name");
    puts("0.quit");
    printf("Please input your choice(1 or 2):");
    scanf("%d",&choice);
    if(choice == 1)
    {
        StringInput(SearchInput,10,"Please input existing student ID");
        //通过链表的LocateElem操作来获取查找到的结点位置
        p = LocateElem(l,SearchInput,"ID");
        if(!p) //找不到
        {
            printf("No find the record!\n");
            return ERROR;
        }
        else
            PrintData(p);
    }
    else if(choice == 2)
    {
        StringInput(SearchInput,10,"Please input existing student name");
        p = LocateElem(l,SearchInput,"name");
        if(!p)
        {
            printf("No find the record!\n");
            return ERROR;
        }
        else 
            PrintData(p);
    }
    printf("Press any key to return\n");
    getchar();
    return OK;
}

/*修改功能*/
Status ModifyStduent(LinkList l)
{
    system("clean");
    Node *p;
    p = l->next;
    char SearchInput[15];
    if(!p)//链表为空
    {
        printf("There aren't students' record.\n");
        return ERROR;
    }
    StringInput(SearchInput,15,"Please input the existing student ID:");
    p = LocateElem(l,SearchInput,"ID");//获得需要修改的结点位置
    if(p)
    {
        PrintData(p);
        StringInput(p->data.name,15,"Input new name:");
        p->data.ProgammingGrade = NumberInput("C language score[0,100]: ");
        p->data.MathGrade = NumberInput("Math score[0,100]: ");
        p->data.EnglishGrade = NumberInput("English score[0,100]: ");
        p->data.sum = p->data.ProgammingGrade + p->data.EnglishGrade + p->data.MathGrade;
        p->data.average = (double)(p->data.sum)/3;
    }
    else
    {
        printf("No find the record!\n");
        return ERROR;
    }
    return OK;
}

/*删除功能*/
Status DeleteStudent(LinkList l)
{
    system("clean");
    int choice;
    char SearchInput[15];
    Node *p,*q;
    p = l->next;
    if(!p)
    {
        printf("There aren't students' record.\n");
        return ERROR;
    }
    //删除界面
    puts("1.Delete by student ID.");
    puts("2.Delete by name.");
    puts("0.quit");
    printf("Please input your choice: ");
    scanf("%d",&choice);
    if(choice == 1)
    {
        StringInput(SearchInput,15,"Please input the existing student ID: ");
        p = LocateElem(l,SearchInput,"ID");//获得需要删除的结点位置
        if(p)
        {
            //链表的删除操作
            q = l;
            while (q->next != p)        
                q = q->next;
            q->next = p->next;
            free(p);
        }
        else
        {
            printf("No find the record!\n");
            return ERROR;
        }
    }
    else if(choice == 2)
    {
        StringInput(SearchInput,15,"Please input the existing student name: ");
        p = LocateElem(l,SearchInput,"name");
        if(p)
        {
            q = l;
            while (q->next != p)        
                q = q->next;
            q->next = p->next;
            free(p);
        }
        else
        {
            printf("No find the record!\n");
            return ERROR;
        }
    }
    printf("delete success!\n");
    getchar();
    return OK;
}