c语言学生学籍管理系统

Question

在用c语言写学生学籍管理系统的时候，不会写加载文件的函数，自己写的导致第二次运行查询不到任何信息，请为我下面这个学生学籍管理系统续写一个加载文件的函数

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct StudentInfo {
    char name[50];
    int id;
    char sex[30];
    int age;
    char major[50];
    int sort;
    float grapoint;
};
struct Course {
    char name[20];
    float score;
    float credit;
    float DKgrapoint;
    int ismakeup;//用来区分补缓考
};
typedef  struct student
{
    struct StudentInfo  info;
    struct Course  courses[10];
}stu;
typedef struct  Lnode
{
    stu  data;
    struct Lnode* next;
}linklist;
void load(linklist*& L);
void showmenu(linklist*& L);
void search(linklist* L);
void add(linklist*& L);
void modify(linklist* L);
void remove(linklist* L);
void save(linklist*& L);
void initlist(linklist*& L);
void insert(linklist*& L, linklist* p);
float compute_DKgpa(float score);
float compute_gpa(linklist* newnode);
int sort_grap(linklist* p, linklist* L);
int main()
{
    linklist* L;
    initlist(L);
    load(L);
    while (1)
    {
        showmenu(L);
    }
    system("pause");
    return 0;
}
void showmenu(linklist*& L)
{
    int num;
    printf("\n\n");
    printf("————————————————————————————————————-\n");
    printf("**********************学生学籍管理系统**********************\n");
    printf("***********************系统功能菜单***************************\n");
    printf("*                      1.查询学生信息                        *\n");
    printf("*                      2.添加学生信息                        *\n");
    printf("*                      3.修改学生信息                        *\n");
    printf("*                      4.删除学生信息                        *\n");
    printf("*                      5.保存信息到文件中                    *\n");
    printf("*                      7.退出系统                            *\n");
    printf("—————————————————————————————————————\n");
    printf("请选择菜单的编号:");
    scanf_s("%d", &num);//输入各个功能对应的序号以此来实现相应的功能
    switch (num) {
    case 1:search(L);
        break;
    case 2:add(L);
        break;
    case 3:modify(L);
        break;
    case 4:remove(L);
        break;
    case 5:save(L);
        break;
    case 6:printf("退出程序成功!\n");
        exit(0);
    default:
        printf("请在1-6之间选择\n");
        system("pause");//提示完成之后显示按任意键继续
    }
}
void initlist(linklist*& L)
{
    L = (linklist*)malloc(sizeof(linklist));
    L->next = NULL;
}
void insert(linklist*& L, linklist* p)//尾插法插入节点
{
    linklist* q;
    q = L;
    while (q->next)
    {
        q = q->next;
    }
    p->next = NULL;
    q->next = p;
}
void add(linklist*& L)
{
    linklist* p;
    p = L;
    int num;
    printf("请输入该名学生的学号:");
    scanf_s("%d", &num);
    while (p->next)
    {
        if (p->data.info.id == num)
        {
            printf("该学生已存在\n");
            break;
        }
        p = p->next;
    }
    if (!p->next)
    {
        linklist* newnode = (linklist*)malloc(sizeof(linklist));
        newnode->data.info.id = num;
        printf("请输入学生名字：");
        scanf_s("%s", newnode->data.info.name, _countof(newnode->data.info.name));
        printf("性别：");
        scanf_s("%s", newnode->data.info.sex, _countof(newnode->data.info.sex));
        printf("年龄：");
        scanf_s("%d", &newnode->data.info.age);
        printf("专业：");
        scanf_s("%s", &newnode->data.info.major, _countof(newnode->data.info.major));
        for (int i = 0; i < 10; i++)
        {
            printf("请输入第%d学科的相关信息:", i + 1);
            printf("请输入该科的名称:");
            scanf_s("%s", newnode->data.courses[i].name, _countof(newnode->data.courses[i].name));
            printf("请输入该门课的考试状态，0代表正常考试，1代表补缓考:");
            scanf_s("%d", &newnode->data.courses[i].ismakeup);
            printf("请输入该门课的考试成绩:");
            scanf_s("%f", &newnode->data.courses[i].score);
            printf("请输入该门课程的学分:");
            scanf_s("%f", &newnode->data.courses[i].credit);
            if (newnode->data.courses[i].ismakeup && newnode->data.courses[i].score >= 60)
                newnode->data.courses[i].score = 60;
            if (newnode->data.courses[i].ismakeup && newnode->data.courses[i].score < 60)
                newnode->data.courses[i].score = 0;
            newnode->data.courses[i].DKgrapoint = compute_DKgpa(newnode->data.courses[i].score);//单科成绩转为绩点
        }
        newnode->data.info.grapoint = compute_gpa(newnode);
        newnode->data.info.sort = sort_grap(newnode, L);
        insert(L, newnode);
        printf("添加学生成功，别忘了保存学生信息!");
    }
}
float compute_DKgpa(float score)
{
    return((score / 10) - 5 + ((int)score % 10) * 0.1);
}
float compute_gpa(linklist* newnode)
{
    double sum1 = 0;
    double sum2 = 0;
    for (int i = 0; i < 10; i++)
    {
        sum1 = sum1 + newnode->data.courses[i].credit;//计算学分总和
        sum2 = sum2 + newnode->data.courses[i].credit * newnode->data.courses[i].DKgrapoint;
    }
    return sum2 / sum1;
}
int sort_grap(linklist* p, linklist* L)
{
    int count1 = 0;
    int count2 = 0;
    linklist* q = L;
    while (q)
    {
        if (p->data.info.grapoint > (q->data.info.grapoint))
            count1++;
        q = q->next;
        count2++;
    }
    return count2 - count1 + 1;
}
void modify(linklist* L)
{
    int num;
    int flag;
    int choice;
    linklist* p;
    p = L;
    printf("请输入您要修改的学生的学号：\n");
    scanf_s("%d", &num);
    while (p->next)
    {
        if (p->data.info.id == num)
        {
            flag = 1;
            printf("请输入您要修改的信息选项：0.学号 1.姓名 2.性别 3.年龄 4.专业 5.各学科6.绩点 7.绩点排名 \n");
            scanf_s("%d", &choice);
            switch (choice)
            {
            case 0:
                printf("请输入您要修改的学号：");
                scanf_s("%d", &num);
                printf("修改的学号为：%d\n", num);
                p->data.info.id = num;
                printf("修改学号成功！\n");
                break;
            case 1:
                char name[50];
                printf("修改后的名字为:\n");
                scanf_s("%s", name, 50);
                strcpy_s(p->data.info.name, name);
                break;
            case 2:
                char sex[50];
                printf("请输入您要修改的性别");
                scanf_s("%s", sex, 50);
                strcpy_s(p->data.info.sex, sex);
                printf("修改性别成功！\n");
                break;
            case 3:
                int age;
                printf("请输入您要修改的年龄：");
                scanf_s("%d", &age);
                p->data.info.age = age;
                printf("修改年龄成功！\n");
                break;
            case 4:
                char major[50];
                printf("请输入您要修改的专业：");
                scanf_s("%s", major, 50);
                strcpy_s(p->data.info.major, major);
                printf("修改专业成功！");
                break;
            case 5:
                char course[50];
                printf("请输入你想修改的课程:\n");
                scanf_s("%s", course, 50);
                for (int i = 0; i < 10; i++)
                {
                    if (course == p->data.info.major)
                    {
                        printf("请输入你想要修改的课程信息的相关选项:0表示课程名1表示学分2表示补缓考状态3表示成绩（包含单科绩点）\n");
                        int num2;
                        scanf_s("%d", &num2);
                        switch (num2)
                        {
                        case 0:
                            char name2[50];
                            printf("请输入你要重新修改的课程名:");
                            scanf_s("%s", name2, _countof(name2));
                            strcpy_s(p->data.courses[i].name, name2);
                            break;
                        case 1:
                            float credit;
                            printf("请输入你想修改的学分为:\n");
                            scanf_s("%f", &credit);
                            p->data.courses[i].credit = credit;
                            break;
                        case 2:
                            int ismakeup;
                            printf("请输入该门课程的补缓考状态,0表示正常，1表示补缓考:\n");
                            scanf_s("%d", &ismakeup);
                            p->data.courses[i].ismakeup = ismakeup;
                            break;
                        case 3:
                            float score;
                            printf("请重新输入该门课程的成绩:\n");
                            scanf_s("%f", &score);
                            p->data.courses[i].score = score;
                            p->data.courses[i].DKgrapoint = compute_DKgpa(score);
                            printf("该门课程的绩点已经自动修改!");
                            break;
                        default:
                            printf("输入错误，请重新进行修改:\n");
                            break;
                        }
                    }
                }
                break;
            case 6:p->data.info.grapoint = compute_gpa(p);
                printf("该名学生的绩点已经修改成功:\n");
                break;
            case 7:
                printf("请修改该名学生的绩点排名:\n");
                p->data.info.sort = sort_grap(p, L);
                printf("修改绩点排名成功:\n");
                break;
            default:printf("请输入正确的选项:\n");
                break;
            }
        }
        p = p->next;
    }
    if (flag != 0)
        printf("该学生不存在:\n");
}
void remove(linklist* L)
{
    int num;
    int flag;
    printf("请输入您要删除的学生的学号：");
    scanf_s("%d", &num);
    linklist* pre = L;
    linklist* p = pre->next;
    while (p)
    {
        if (p->data.info.id == num)
        {
            flag = 1;
            pre->next = p->next;
            free(p);
            printf("成功删除学生！\n");
            break;
        }
        pre = p;
        p = p->next;
    }
    if (flag != 0)
        printf("这个学生不存在!\n");
}
void search(linklist* L)
{
    int num;
    int flag;
    printf("1.按学号查询：\n");
    printf("2.按姓名查询：\n");
    printf("请输入查询方式：");
    scanf_s("%d", &flag);
    if (flag == 1)
    {
        printf("请输入该学生的学号：");
        scanf_s("%d", &num);
        linklist* p = L->next;
        while (p != NULL)
        {
            if (p->data.info.id == num)
            {
                printf("学号：%d\n", p->data.info.id);
                printf("姓名：%s\n", p->data.info.name);
                printf("性别：%s\n", p->data.info.sex);
                printf("年龄：%d\n", p->data.info.age);
                printf("绩点：%f\n", p->data.info.grapoint);
                printf("绩点排名：%d\n", p->data.info.sort);
                printf("专业：%s\n", p->data.info.major);
                for (int i = 0; i < 10; i++)
                    printf("%s:  %f   绩点:%f\n", p->data.courses[i].name, p->data.courses[i].score, p->data.courses[i].DKgrapoint);
                break;
            }
            p = p->next;
        }
        if (p == NULL)
            printf("该学生不存在\n");
    }
    else
    {
        char name[60];
        printf("请输入该学生的姓名：");
        scanf_s("%s", name, 60);
        linklist* q = L->next;
        while (q)
        {
            if (strcmp(q->data.info.name,name)== 0)
            {
                printf("学号：%d\n", q->data.info.id);
                printf("姓名：%s\n", q->data.info.name);
                printf("性别：%s\n", q->data.info.sex);
                printf("年龄：%d\n", q->data.info.age);
                printf("绩点：%f\n", q->data.info.grapoint);
                printf("绩点排名：%d\n", q->data.info.sort);
                printf("专业：%s\n", q->data.info.major);
                for (int i = 0; i < 10; i++)
                    printf("%s:  %f   绩点:%f\n", q->data.courses[i].name, q->data.courses[i].score, q->data.courses[i].DKgrapoint);
                break;
            }
            q = q->next;
        }
        if (!q)
            printf("该学生不存在\n");
    }
}
void save(linklist*& L)
{
    FILE* fp;
    linklist* p = L->next;
    if ((fp = fopen("student.txt", "w")) == NULL)
    {
        printf("不能打开此文件，请按任意键退出\n");
        exit(1); //异常退出
    }
    while (p)
    {
        struct Course {
            char name[20];
            double score;
            double credit;
            double DKgrapoint;
            int ismakeup;//用来区分补缓考
        };
        fprintf(fp, "%d %s %s %d %f %d %s\n", p->data.info.id, p->data.info.name, p->data.info.sex, p->data.info.age, p->data.info.grapoint, p->data.info.sort, p->data.info.major);
        for (int i = 0; i < 10; i++)
            fprintf(fp, "%s %f %f %f %d\n", p->data.courses[i].name, p->data.courses[i].score, p->data.courses[i].credit, p->data.courses[i].DKgrapoint, p->data.courses[i].ismakeup);
        p = p->next;
    }
    printf("保存成功:\n");
    fclose(fp);
}

Answer 1

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为了确保在第二次运行时能正确读取之前保存的学生信息，你需要编写一个load函数，该函数可以从文件中读取数据并构建链表。以下是load函数的实现，它将从student.txt文件中读取数据并填充链表。

void load(linklist*& L) {
    FILE* fp;
    if ((fp = fopen("student.txt", "r")) == NULL) {
        printf("文件打开失败，将创建一个新的空链表。\n");
        return;
    }

    int id;
    char name[50];
    char sex[30];
    int age;
    float grapoint;
    int sort;
    char major[50];

    while (fscanf(fp, "%d %s %s %d %f %d %s", &id, name, sex, &age, &grapoint, &sort, major) != EOF) {
        linklist* newnode = (linklist*)malloc(sizeof(linklist));
        newnode->data.info.id = id;
        strcpy(newnode->data.info.name, name);
        strcpy(newnode->data.info.sex, sex);
        newnode->data.info.age = age;
        newnode->data.info.grapoint = grapoint;
        newnode->data.info.sort = sort;
        strcpy(newnode->data.info.major, major);

        for (int i = 0; i < 10; i++) {
            fscanf(fp, "%s %f %f %f %d", newnode->data.courses[i].name, &newnode->data.courses[i].score, &newnode->data.courses[i].credit, &newnode->data.courses[i].DKgrapoint, &newnode->data.courses[i].ismakeup);
        }

        insert(L, newnode);
    }

    fclose(fp);
}

这个load函数首先尝试打开student.txt文件。如果文件不存在或无法打开，它会打印一条消息并返回，不执行任何操作，从而允许程序创建一个新的空链表。如果文件成功打开，函数将开始读取每个学生的信息，并为每个学生创建一个新的linklist节点。通过fscanf函数读取每一行的数据，并将其存储到新创建的节点中。一旦所有字段都已读取，该节点就会被插入到链表中。

注意，在读取课程信息时，fscanf函数用于从文件中读取每一门课程的详细信息。由于每行数据的格式与fscanf的要求相匹配，所以这个过程是自动且高效的。

最后，当所有数据都已读取完毕后，文件会被关闭，确保资源得到释放。这样，无论何时启动程序，只要student.txt文件存在，load函数都会正确地加载所有学生信息。