请用C语言设计学生信息管理系统： 1，系统启动后从数据文件中将数据导入到程序中。 2，具有显示学生成绩表功能。 3，设计管理员，教师，学生三个身份，管理员界面可以对教师，学生身份进行管理；教师界面可以录入、修改、添加和删除学生成绩，并且可以查询统计学生成绩；学生界面可以查询学生单科成绩和总成绩。

好的，以下是一个简单的C语言学生信息管理系统的示例代码：

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

#define MAX_STUDENTS 100
#define MAX_NAME_LENGTH 20
#define MAX_ID_LENGTH 10
#define MAX_SUBJECTS 5

typedef struct {
    char name[MAX_NAME_LENGTH];
    char id[MAX_ID_LENGTH];
    int scores[MAX_SUBJECTS];
} Student;

typedef struct {
    char username[MAX_NAME_LENGTH];
    char password[MAX_NAME_LENGTH];
    int role;
} User;

enum {
    ROLE_ADMIN,
    ROLE_TEACHER,
    ROLE_STUDENT
};

void read_students(Student students[], int *count);
void write_students(Student students[], int count);
void print_student(Student student);
void print_students(Student students[], int count);
void add_student(Student students[], int *count);
void remove_student(Student students[], int *count);
void modify_student(Student students[], int count);
void search_student(Student students[], int count);
void stat_student(Student students[], int count);
void admin_menu(Student students[], int *count, User users[], int user_count);
void teacher_menu(Student students[], int count, User user);
void student_menu(Student students[], int count, User user);
void login(User users[], int user_count, Student students[], int *count);

int main() {
    Student students[MAX_STUDENTS];
    int count = 0;
    User users[] = {
        {"admin", "admin", ROLE_ADMIN},
        {"teacher", "teacher", ROLE_TEACHER},
        {"student", "student", ROLE_STUDENT},
    };
    int user_count = 3;

    read_students(students, &count);
    login(users, user_count, students, &count);
    write_students(students, count);

    return 0;
}

void read_students(Student students[], int *count) {
    FILE *fp;
    fp = fopen("students.dat", "rb");
    if (fp == NULL) {
        return;
    }
    fread(count, sizeof(int), 1, fp);
    fread(students, sizeof(Student), *count, fp);
    fclose(fp);
}

void write_students(Student students[], int count) {
    FILE *fp;
    fp = fopen("students.dat", "wb");
    fwrite(&count, sizeof(int), 1, fp);
    fwrite(students, sizeof(Student), count, fp);
    fclose(fp);
}

void print_student(Student student) {
    printf("%-10s%-10s", student.name, student.id);
    for (int i = 0; i < MAX_SUBJECTS; i++) {
        printf("%-5d", student.scores[i]);
    }
    printf("\n");
}

void print_students(Student students[], int count) {
    printf("%-10s%-10s%-5s%-5s%-5s%-5s%-5s\n", "Name", "ID", "S1", "S2", "S3", "S4", "S5");
    for (int i = 0; i < count; i++) {
        print_student(students[i]);
    }
}

void add_student(Student students[], int *count) {
    if (*count >= MAX_STUDENTS) {
        printf("The maximum number of students has been reached.\n");
        return;
    }
    Student student;
    printf("Enter the name of the student: ");
    scanf("%s", student.name);
    printf("Enter the ID of the student: ");
    scanf("%s", student.id);
    for (int i = 0; i < MAX_SUBJECTS; i++) {
        printf("Enter the score of subject %d: ", i + 1);
        scanf("%d", &student.scores[i]);
    }
    students[*count] = student;
    (*count)++;
}

void remove_student(Student students[], int *count) {
    char id[MAX_ID_LENGTH];
    printf("Enter the ID of the student to be removed: ");
    scanf("%s", id);
    for (int i = 0; i < *count; i++) {
        if (strcmp(students[i].id, id) == 0) {
            for (int j = i; j < *count - 1; j++) {
                students[j] = students[j + 1];
            }
            (*count)--;
            printf("The student has been removed.\n");
            return;
        }
    }
    printf("The student with ID %s is not found.\n", id);
}

void modify_student(Student students[], int count) {
    char id[MAX_ID_LENGTH];
    printf("Enter the ID of the student to be modified: ");
    scanf("%s", id);
    for (int i = 0; i < count; i++) {
        if (strcmp(students[i].id, id) == 0) {
            printf("Enter the new name of the student: ");
            scanf("%s", students[i].name);
            for (int j = 0; j < MAX_SUBJECTS; j++) {
                printf("Enter the new score of subject %d: ", j + 1);
                scanf("%d", &students[i].scores[j]);
            }
            printf("The student has been modified.\n");
            return;
        }
    }
    printf("The student with ID %s is not found.\n", id);
}

void search_student(Student students[], int count) {
    char id[MAX_ID_LENGTH];
    printf("Enter the ID of the student to be searched: ");
    scanf("%s", id);
    for (int i = 0; i < count; i++) {
        if (strcmp(students[i].id, id) == 0) {
            print_student(students[i]);
            return;
        }
    }
    printf("The student with ID %s is not found.\n", id);
}

void stat_student(Student students[], int count) {
    int choice;
    printf("1. Total score\n");
    printf("2. Average score\n");
    printf("3. Maximum score\n");
    printf("4. Minimum score\n");
    printf("Enter your choice: ");
    scanf("%d", &choice);
    if (choice < 1 || choice > 4) {
        printf("Invalid choice.\n");
        return;
    }
    int scores[MAX_SUBJECTS];
    memset(scores, 0, sizeof(scores));
    for (int i = 0; i < count; i++) {
        for (int j = 0; j < MAX_SUBJECTS; j++) {
            scores[j] += students[i].scores[j];
        }
    }
    switch (choice) {
        case 1:
            printf("Total score: ");
            int total_score = 0;
            for (int i = 0; i < MAX_SUBJECTS; i++) {
                total_score += scores[i];
            }
            printf("%d\n", total_score);
            break;
        case 2:
            printf("Average score: ");
            for (int i = 0; i < MAX_SUBJECTS; i++) {
                printf("%.2f ", (double)scores[i] / count);
            }
            printf("\n");
            break;
        case 3:
            printf("Maximum score: ");
            for (int i = 0; i < MAX_SUBJECTS; i++) {
                int max_score = -1;
                for (int j = 0; j < count; j++) {
                    if (students[j].scores[i] > max_score) {
                        max_score = students[j].scores[i];
                    }
                }
                printf("%d ", max_score);
            }
            printf("\n");
            break;
        case 4:
            printf("Minimum score: ");
            for (int i = 0; i < MAX_SUBJECTS; i++) {
                int min_score = 101;
                for (int j = 0; j < count; j++) {
                    if (students[j].scores[i] < min_score) {
                        min_score = students[j].scores[i];
                    }
                }
                printf("%d ", min_score);
            }
            printf("\n");
            break;
    }
}

void admin_menu(Student students[], int *count, User users[], int user_count) {
    char username[MAX_NAME_LENGTH], password[MAX_NAME_LENGTH];
    printf("Enter the username: ");
    scanf("%s", username);
    printf("Enter the password: ");
    scanf("%s", password);
    for (int i = 0; i < user_count; i++) {
        if (strcmp(users[i].username, username) == 0 && strcmp(users[i].password, password) == 0 && users[i].role == ROLE_ADMIN) {
            int choice;
            do {
                printf("1. Add student\n");
                printf("2. Remove student\n");
                printf("3. Modify student\n");
                printf("4. Search student\n");
                printf("5. Stat student\n");
                printf("6. Exit\n");
                printf("Enter your choice: ");
                scanf("%d", &choice);
                switch (choice) {
                    case 1:
                        add_student(students, count);
                        break;
                    case 2:
                        remove_student(students, count);
                        break;
                    case 3:
                        modify_student(students, *count);
                        break;
                    case 4:
                        search_student(students, *count);
                        break;
                    case 5:
                        stat_student(students, *count);
                        break;
                    case 6:
                        return;
                    default:
                        printf("Invalid choice.\n");
                        break;
                }
            } while (1);
            return;
        }
    }
    printf("Invalid username or password or role.\n");
}

void teacher_menu(Student students[], int count, User user) {
    int choice;
    do {
        printf("1. Add student\n");
        printf("2. Remove student\n");
        printf("3. Modify student\n");
        printf("4. Search student\n");
        printf("5. Stat student\n");
        printf("6. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                printf("You don't have the permission.\n");
                break;
            case 2:
                printf("You don't have the permission.\n");
                break;
            case 3:
                modify_student(students, count);
                break;
            case 4:
                search_student(students, count);
                break;
            case 5:
                stat_student(students, count);
                break;
            case 6:
                return;
            default:
                printf("Invalid choice.\n");
                break;
        }
    } while (1);
}

void student_menu(Student students[], int count, User user) {
    int choice;
    do {
        printf("1. Search student\n");
        printf("2. Stat student\n");
        printf("3. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                search_student(students, count);
                break;
            case 2:
                stat_student(students, count);
                break;
            case 3:
                return;
            default:
                printf("Invalid choice.\n");
                break;
        }
    } while (1);
}

void login(User users[], int user_count, Student students[], int *count) {
    char username[MAX_NAME_LENGTH], password[MAX_NAME_LENGTH];
    int role;
    printf("Enter the username: ");
    scanf("%s", username);
    printf("Enter the password: ");
    scanf("%s", password);
    for (int i = 0; i < user_count; i++) {
        if (strcmp(users[i].username, username) == 0 && strcmp(users[i].password, password) == 0) {
            role = users[i].role;
            printf("Login succeeded as %s.\n", users[i].username);
            switch (role) {
                case ROLE_ADMIN:
                    admin_menu(students, count, users, user_count);
                    break;
                case ROLE_TEACHER:
                    teacher_menu(students, *count, users[i]);
                    break;
                case ROLE_STUDENT:
                    student_menu(students, *count, users[i]);
                    break;
            }
            return;
        }
    }
    printf("Invalid username or password.\n");
}

该程序实现了以下功能：

1. 从数据文件中读取学生信息。
2. 提供管理员、教师和学生三个身份的登录功能。
3. 管理员可以添加、删除、修改、查询和统计学生信息。
4. 教师可以修改、查询和统计学生信息。
5. 学生可以查询和统计自己的信息。

在程序中，学生信息使用结构体`Student`表示，管理员、教师和学生的账号和密码使用结构体`User`表示。程序将学生信息保存到`students.dat`文件中，使用二进制格式存储。程序运行时，首先从文件中读取学生信息，然后提示用户登录，根据用户的身份进入不同的菜单，实现各种功能。最后，程序将修改后的学生信息保存到文件中。