学生信息管理系统下设管理员、教师、学生三个部分。管理员可以对教师和学生的身份进行管理。教师的权限在成绩维护与查询，其中成绩维护包括录入 、修改、删除、添加，查询功能包括各种方式的成绩查询、统计。学生端则可以查询单科成绩或总成绩

好的，以下是使用 C 语言实现的学生信息管理系统的部分代码，包括管理员、教师和学生三个部分的功能。为了简化代码，这里使用了结构体和数组来存储学生和教师的信息。

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

#define MAX_STUDENT 100
#define MAX_TEACHER 100

// 学生和教师信息结构体
struct student {
    char name[20];
    int id;
    int grade;
    int class;
    char phone[20];
    int math;
    int english;
    int physics;
    int chemistry;
    int total;
};

struct teacher {
    char name[20];
    char password[20];
};

// 全局变量
struct student students[MAX_STUDENT];
int student_cnt = 0;
struct teacher teachers[MAX_TEACHER];
int teacher_cnt = 0;

// 函数声明
void admin_login();
void admin_menu();
void add_teacher();
void add_student();
void modify_student();
void delete_student();
void query_student();
void teacher_login();
void teacher_menu();
void add_score();
void modify_score();
void delete_score();
void query_score();

int main() {
    while (1) {
        printf("请选择用户类型：\n");
        printf("1. 管理员\n");
        printf("2. 教师\n");
        printf("3. 学生\n");
        printf("4. 退出\n");
        int choice;
        scanf("%d", &choice);
        switch (choice) {
            case 1: admin_login(); break;
            case 2: teacher_login(); break;
            case 3: // 学生功能暂未实现
            case 4: return 0;
            default: printf("无效选择，请重新输入。\n");
        }
    }
}

// 管理员登录
void admin_login() {
    printf("请输入管理员账号和密码：\n");
    char username[20], password[20];
    scanf("%s %s", username, password);
    if (strcmp(username, "admin") == 0 && strcmp(password, "admin") == 0) {
        admin_menu();
    } else {
        printf("账号或密码错误，请重新登录。\n");
    }
}

// 管理员菜单
void admin_menu() {
    while (1) {
        printf("请选择操作：\n");
        printf("1. 添加教师\n");
        printf("2. 添加学生\n");
        printf("3. 修改学生信息\n");
        printf("4. 删除学生信息\n");
        printf("5. 查询学生信息\n");
        printf("6. 退出\n");
        int choice;
        scanf("%d", &choice);
        switch (choice) {
            case 1: add_teacher(); break;
            case 2: add_student(); break;
            case 3: modify_student(); break;
            case 4: delete_student(); break;
            case 5: query_student(); break;
            case 6: return;
            default: printf("无效选择，请重新输入。\n");
        }
    }
}

// 添加教师
void add_teacher() {
    if (teacher_cnt >= MAX_TEACHER) {
        printf("教师信息已满，无法添加。\n");
        return;
    }
    printf("请输入教师姓名和密码：\n");
    char name[20], password[20];
    scanf("%s %s", name, password);
    strcpy(teachers[teacher_cnt].name, name);
    strcpy(teachers[teacher_cnt].password, password);
    teacher_cnt++;
    printf("教师信息添加成功。\n");
}

// 添加学生
void add_student() {
    if (student_cnt >= MAX_STUDENT) {
        printf("学生信息已满，无法添加。\n");
        return;
    }
    printf("请输入学生姓名、学号、年级、班级和联系方式：\n");
    char name[20], phone[20];
    int id, grade, class;
    scanf("%s %d %d %d %s", name, &id, &grade, &class, phone);
    strcpy(students[student_cnt].name, name);
    students[student_cnt].id = id;
    students[student_cnt].grade = grade;
    students[student_cnt].class = class;
    strcpy(students[student_cnt].phone, phone);
    students[student_cnt].math = -1;
    students[student_cnt].english = -1;
    students[student_cnt].physics = -1;
    students[student_cnt].chemistry = -1;
    students[student_cnt].total = -4;
    student_cnt++;
    printf("学生信息添加成功。\n");
}

// 修改学生信息
void modify_student() {
    printf("请输入学生学号：\n");
    int id;
    scanf("%d", &id);
    int index = -1;
    for (int i = 0; i < student_cnt; i++) {
        if (students[i].id == id) {
            index = i;
            break;
        }
    }
    if (index < 0) {
        printf("找不到学生信息，请重新输入。\n");
        return;
    }
    printf("请输入修改后的学生姓名、年级、班级和联系方式：\n");
    char name[20], phone[20];
    int grade, class;
    scanf("%s %d %d %s", name, &grade, &class, phone);
    strcpy(students[index].name, name);
    students[index].grade = grade;
    students[index].class = class;
    strcpy(students[index].phone, phone);
    printf("学生信息修改成功。\n");
}

// 删除学生信息
void delete_student() {
    printf("请输入学生学号：\n");
    int id;
    scanf("%d", &id);
    int index = -1;
    for (int i = 0; i < student_cnt; i++) {
        if (students[i].id == id) {
            index = i;
            break;
        }
    }
    if (index < 0) {
        printf("找不到学生信息，请重新输入。\n");
        return;
    }
    for (int i = index; i < student_cnt - 1; i++) {
        students[i] = students[i + 1];
    }
    student_cnt--;
    printf("学生信息删除成功。\n");
}

// 查询学生信息
void query_student() {
    printf("请输入学生学号：\n");
    int id;
    scanf("%d", &id);
    int index = -1;
    for (int i = 0; i < student_cnt; i++) {
        if (students[i].id == id) {
            index = i;
            break;
        }
    }
    if (index < 0) {
        printf("找不到学生信息，请重新输入。\n");
        return;
    }
    printf("学生姓名：%s\n", students[index].name);
    printf("学生学号：%d\n", students[index].id);
    printf("学生年级：%d\n", students[index].grade);
    printf("学生班级：%d\n", students[index].class);
    printf("联系方式：%s\n", students[index].phone);
}

// 教师登录
void teacher_login() {
    printf("请输入教师姓名和密码：\n");
    char name[20], password[20];
    scanf("%s %s", name, password);
    int index = -1;
    for (int i = 0; i < teacher_cnt; i++) {
        if (strcmp(teachers[i].name, name) == 0 && strcmp(teachers[i].password, password) == 0) {
            index = i;
            break;
        }
    }
    if (index < 0) {
        printf("教师姓名或密码错误，请重新登录。\n");
        return;
    }
    teacher_menu();
}

// 教师菜单
void teacher_menu() {
    while (1) {
        printf("请选择操作：\n");
        printf("1. 添加成绩\n");
        printf("2. 修改成绩\n");
        printf("3. 删除成绩\n");
        printf("4. 查询成绩\n");
        printf("5. 退出\n");
        int choice;
        scanf("%d", &choice);
        switch (choice) {
            case 1: add_score(); break;
            case 2: modify_score(); break;
            case 3: delete_score(); break;
            case 4: query_score(); break;
            case 5: return;
            default: printf("无效选择，请重新输入。\n");
        }
    }
}

// 添加成绩
void add_score() {
    printf("请输入学生学号和四门课程的成绩：\n");
    int id, math, english, physics, chemistry;
    scanf("%d %d %d %d %d", &id, &math, &english, &physics, &chemistry);
    int index = -1;
    for (int i = 0; i < student_cnt; i++) {
        if (students[i].id == id) {
            index = i;
            break;
        }
    }
    if (index < 0) {
        printf("找不到学生信息，请重新输入。\n");
        return;
    }
    students[index].math = math;
    students[index].english = english;
    students[index].physics = physics;
    students[index].chemistry = chemistry;
    students[index].total = math + english + physics + chemistry;
    printf("成绩添加成功。\n");
}

// 修改成绩
void modify_score() {
    printf("请输入学生学号和需要修改的课程：\n");
    int id;
    char course[20];
    scanf("%d %s", &id, course);
    int index = -1;
    for (int i = 0; i < student_cnt; i++) {
        if (students[i].id == id) {
            index = i;
            break;
        }
    }
    if (index < 0) {
        printf("找不到学生信息，请重新输入。\n");
        return;
    }
    int score;
    if (strcmp(course, "math") == 0) {
        printf("请输入修改后的数学成绩：\n");
        scanf("%d", &score);
        students[index].math = score;
    } else if (strcmp(course, "english") == 0) {
        printf("请输入修改后的英语成绩：\n");
        scanf("%d", &score);
        students[index].english = score;
    } else if (strcmp(course, "physics") == 0) {
        printf("请输入修改后的物理成绩：\n");
        scanf("%d", &score);
        students[index].physics = score;
    } else if (strcmp(course, "chemistry") == 0) {
        printf("请输入修改后的化学成绩：\n");
        scanf("%d", &score);
        students[index].chemistry = score;
    } else {
        printf("无效课程，请重新输入。\n");
        return;
    }
    students[index].total = students[index].math + students[index].english + students[index].physics + students[index].chemistry;
    printf("成绩修改成功。\n");
}

// 删除成绩
void delete_score() {
    printf("请输入学生学号和需要删除的课程：\n");
    int id;
    char course[20];
    scanf("%d %s", &id, course);
    int index = -1;
    for (int i = 0; i < student_cnt; i++) {
        if (students[i].id == id) {
            index = i;
            break;
        }
    }
    if (index < 0) {
        printf("找不到学生信息，请重新输入。\n");
        return;
    }
    if (strcmp(course, "math") == 0) {
        students[index].math = -1;
    } else if (strcmp(course, "english") == 0) {
        students[index].english = -1;
    } else if (strcmp(course, "physics") == 0) {
        students