帮我用C语言写一个学生成绩管理系统

好的，以下是一个简单的学生成绩管理系统的C语言代码：

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

#define MAX_STUDENTS 100  // 最大学生数
#define NAME_LENGTH 20    // 学生姓名最大长度
#define COURSE_NUM 3      // 学生科目数

// 学生信息结构体
typedef struct {
    char name[NAME_LENGTH];
    int scores[COURSE_NUM];
    int total_score;
    float avg_score;
} Student;

// 学生管理系统结构体
typedef struct {
    Student students[MAX_STUDENTS];  // 学生数组
    int student_count;               // 学生数量
} StudentManager;

// 显示菜单
void show_menu() {
    printf("1. 添加学生信息\n");
    printf("2. 显示所有学生信息\n");
    printf("3. 按姓名查询学生信息\n");
    printf("4. 按总分排序并显示学生信息\n");
    printf("5. 退出\n");
}

// 添加学生信息
void add_student(StudentManager* manager) {
    if (manager->student_count >= MAX_STUDENTS) {
        printf("学生数量已达到上限，无法添加新学生！\n");
        return;
    }

    Student new_student;
    printf("请输入学生姓名：");
    scanf("%s", new_student.name);

    printf("请输入学生各科成绩：\n");
    for (int i = 0; i < COURSE_NUM; i++) {
        printf("科目 %d：", i + 1);
        scanf("%d", &new_student.scores[i]);
    }

    // 计算总分和平均分
    new_student.total_score = 0;
    for (int i = 0; i < COURSE_NUM; i++) {
        new_student.total_score += new_student.scores[i];
    }
    new_student.avg_score = (float)new_student.total_score / COURSE_NUM;

    // 添加学生到管理系统中
    manager->students[manager->student_count] = new_student;
    manager->student_count++;
    printf("成功添加学生信息！\n");
}

// 显示所有学生信息
void show_all_students(StudentManager* manager) {
    if (manager->student_count == 0) {
        printf("学生数量为0，无法显示学生信息！\n");
        return;
    }

    printf("所有学生信息如下：\n");
    printf("姓名\t科目1\t科目2\t科目3\t总分\t平均分\n");
    for (int i = 0; i < manager->student_count; i++) {
        Student student = manager->students[i];
        printf("%s\t", student.name);
        for (int j = 0; j < COURSE_NUM; j++) {
            printf("%d\t", student.scores[j]);
        }
        printf("%d\t%.2f\n", student.total_score, student.avg_score);
    }
}

// 按姓名查询学生信息
void search_student_by_name(StudentManager* manager) {
    if (manager->student_count == 0) {
        printf("学生数量为0，无法查询学生信息！\n");
        return;
    }

    char name[NAME_LENGTH];
    printf("请输入要查询的学生姓名：");
    scanf("%s", name);

    int found = 0;
    printf("查询到的学生信息如下：\n");
    printf("姓名\t科目1\t科目2\t科目3\t总分\t平均分\n");
    for (int i = 0; i < manager->student_count; i++) {
        Student student = manager->students[i];
        if (strcmp(student.name, name) == 0) {
            printf("%s\t", student.name);
            for (int j = 0; j < COURSE_NUM; j++) {
                printf("%d\t", student.scores[j]);
            }
            printf("%d\t%.2f\n", student.total_score, student.avg_score);
            found = 1;
        }
    }
    if (!found) {
        printf("未查询到学生信息！\n");
    }
}

// 比较函数，用于按总分排序学生信息
int compare_students_by_total_score(const void* a, const void* b) {
    Student* student_a = (Student*)a;
    Student* student_b = (Student*)b;
    if (student_a->total_score < student_b->total_score) {
        return 1;
    } else if (student_a->total_score > student_b->total_score) {
        return -1;
    } else {
        return 0;
    }
}

// 按总分排序并显示学生信息
void sort_and_show_students_by_total_score(StudentManager* manager) {
    if (manager->student_count == 0) {
        printf("学生数量为0，无法排序和显示学生信息！\n");
        return;
    }

    // 按总分排序
    qsort(manager->students, manager->student_count, sizeof(Student), compare_students_by_total_score);

    // 显示排序后的学生信息
    printf("按总分排序后的学生信息如下：\n");
    printf("姓名\t科目1\t科目2\t科目3\t总分\t平均分\n");
    for (int i = 0; i < manager->student_count; i++) {
        Student student = manager->students[i];
        printf("%s\t", student.name);
        for (int j = 0; j < COURSE_NUM; j++) {
            printf("%d\t", student.scores[j]);
        }
        printf("%d\t%.2f\n", student.total_score, student.avg_score);
    }
}

int main() {
    StudentManager manager;
    manager.student_count = 0;

    int choice = 0;
    do {
        show_menu();
        printf("请输入选项：");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_student(&manager);
                break;
            case 2:
                show_all_students(&manager);
                break;
            case 3:
                search_student_by_name(&manager);
                break;
            case 4:
                sort_and_show_students_by_total_score(&manager);
                break;
            case 5:
                printf("谢谢使用！\n");
                break;
            default:
                printf("无效选项，请重新选择！\n");
        }
    } while (choice != 5);

    return 0;
}

该学生成绩管理系统实现了添加学生信息、显示所有学生信息、按姓名查询学生信息、按总分排序并显示学生信息等功能。在程序中使用了结构体、函数等C语言特性，可以作为学生们学习C语言的一个小项目。