请给出同学录管理系统的c语言代码 功能要求: (1)、程序启动后显示主菜单，包括下面的选项:1.显示班级列表 2.增加班级 3.删除班级 4、班级同学加入 5.班级同学删除 6.同学录显示 7.同学录存盘 8.同学录文件调入 9.退出 (2)按下相应的按键后进入各自的子功能，每个子功能执行完毕后，返团并显示主菜单 功能说明: ①，显示班级列表:在屏幕显示已登记的班级总数，及各班级名称及加入同学人数。② 增加班级:输入班级信息，包括班号，入学年份，毕业年份。③.删除班级:输入要删除的班号，删除该班级信息。 ④班级同学加入:输入同学姓名，性别，班号，学号。 ⑤.班级同学删除:输入班名，学号，删除同学信息，⑥、同学录显示:输入班号，显示该班的同学列表， ⑦.同学录存盘:输入文件名，将同学录信息存入文件。 ⑧.同学录文件调入:输入文件名，读取文件将数据调入，重新生成同学录信息⑨.退出:退出程序，返回 操作系统

好的，根据您提供的功能要求，以下是同学录管理系统的C语言代码示例：

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

#define MAX_CLASS_NUM 10
#define MAX_STUDENT_NUM 100

struct Student {
    char name[20];
    char gender[3];
    char class_id[10];
    char student_id[20];
};

struct Class {
    char id[10];
    char enter_year[5];
    char graduate_year[5];
    int student_num;
    struct Student students[MAX_STUDENT_NUM];
};

struct Class classes[MAX_CLASS_NUM];
int class_num = 0;

void show_menu();
void show_class_list();
void add_class();
void delete_class();
void add_student();
void delete_student();
void show_student_list();
void save_to_file();
void load_from_file();

int main() {
    while (1) {
        show_menu();
        int choice;
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                show_class_list();
                break;
            case 2:
                add_class();
                break;
            case 3:
                delete_class();
                break;
            case 4:
                add_student();
                break;
            case 5:
                delete_student();
                break;
            case 6:
                show_student_list();
                break;
            case 7:
                save_to_file();
                break;
            case 8:
                load_from_file();
                break;
            case 9:
                printf("Goodbye!\n");
                exit(0);
            default:
                printf("Invalid input, please try again.\n");
        }
    }
}

void show_menu() {
    printf("Please select an option:\n");
    printf("1. Show class list\n");
    printf("2. Add class\n");
    printf("3. Delete class\n");
    printf("4. Add student\n");
    printf("5. Delete student\n");
    printf("6. Show student list\n");
    printf("7. Save to file\n");
    printf("8. Load from file\n");
    printf("9. Quit\n");
}

void show_class_list() {
    printf("Class number: %d\n", class_num);
    printf("Class ID\tEnter year\tGraduate year\tStudent number\n");
    for (int i = 0; i < class_num; i++) {
        printf("%s\t\t%s\t\t%s\t\t%d\n", classes[i].id, classes[i].enter_year, classes[i].graduate_year, classes[i].student_num);
    }
}

void add_class() {
    if (class_num >= MAX_CLASS_NUM) {
        printf("Class number has reached the limit.\n");
        return;
    }
    printf("Please enter the class ID: ");
    scanf("%s", classes[class_num].id);
    printf("Please enter the enter year: ");
    scanf("%s", classes[class_num].enter_year);
    printf("Please enter the graduate year: ");
    scanf("%s", classes[class_num].graduate_year);
    classes[class_num].student_num = 0;
    class_num++;
}

void delete_class() {
    char id[10];
    printf("Please enter the class ID: ");
    scanf("%s", id);
    int index = -1;
    for (int i = 0; i < class_num; i++) {
        if (strcmp(classes[i].id, id) == 0) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        printf("Class not found.\n");
        return;
    }
    for (int i = index; i < class_num - 1; i++) {
        classes[i] = classes[i + 1];
    }
    class_num--;
    printf("Class deleted.\n");
}

void add_student() {
    char class_id[10];
    printf("Please enter the class ID: ");
    scanf("%s", class_id);
    int index = -1;
    for (int i = 0; i < class_num; i++) {
        if (strcmp(classes[i].id, class_id) == 0) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        printf("Class not found.\n");
        return;
    }
    if (classes[index].student_num >= MAX_STUDENT_NUM) {
        printf("Student number has reached the limit.\n");
        return;
    }
    printf("Please enter the student name: ");
    scanf("%s", classes[index].students[classes[index].student_num].name);
    printf("Please enter the student gender: ");
    scanf("%s", classes[index].students[classes[index].student_num].gender);
    printf("Please enter the student ID: ");
    scanf("%s", classes[index].students[classes[index].student_num].student_id);
    strcpy(classes[index].students[classes[index].student_num].class_id, class_id);
    classes[index].student_num++;
}

void delete_student() {
    char class_id[10];
    char student_id[20];
    printf("Please enter the class ID: ");
    scanf("%s", class_id);
    printf("Please enter the student ID: ");
    scanf("%s", student_id);
    int class_index = -1;
    int student_index = -1;
    for (int i = 0; i < class_num; i++) {
        if (strcmp(classes[i].id, class_id) == 0) {
            class_index = i;
            break;
        }
    }
    if (class_index == -1) {
        printf("Class not found.\n");
        return;
    }
    for (int i = 0; i < classes[class_index].student_num; i++) {
        if (strcmp(classes[class_index].students[i].student_id, student_id) == 0) {
            student_index = i;
            break;
        }
    }
    if (student_index == -1) {
        printf("Student not found.\n");
        return;
    }
    for (int i = student_index; i < classes[class_index].student_num - 1; i++) {
        classes[class_index].students[i] = classes[class_index].students[i + 1];
    }
    classes[class_index].student_num--;
    printf("Student deleted.\n");
}

void show_student_list() {
    char class_id[10];
    printf("Please enter the class ID: ");
    scanf("%s", class_id);
    int index = -1;
    for (int i = 0; i < class_num; i++) {
        if (strcmp(classes[i].id, class_id) == 0) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        printf("Class not found.\n");
        return;
    }
    printf("Student number: %d\n", classes[index].student_num);
    printf("Student name\tGender\tStudent ID\n");
    for (int i = 0; i < classes[index].student_num; i++) {
        printf("%s\t\t%s\t%s\n", classes[index].students[i].name, classes[index].students[i].gender, classes[index].students[i].student_id);
    }
}

void save_to_file() {
    char filename[20];
    printf("Please enter the file name: ");
    scanf("%s", filename);
    FILE *fp;
    fp = fopen(filename, "wb");
    if (fp == NULL) {
        printf("Failed to open file.\n");
        return;
    }
    fwrite(&class_num, sizeof(int), 1, fp);
    fwrite(classes, sizeof(struct Class), class_num, fp);
    fclose(fp);
    printf("Data saved.\n");
}

void load_from_file() {
    char filename[20];
    printf("Please enter the file name: ");
    scanf("%s", filename);
    FILE *fp;
    fp = fopen(filename, "rb");
    if (fp == NULL) {
        printf("Failed to open file.\n");
        return;
    }
    fread(&class_num, sizeof(int), 1, fp);
    fread(classes, sizeof(struct Class), class_num, fp);
    fclose(fp);
    printf("Data loaded.\n");
}

注意：以上代码仅为示例，可能存在不足之处，需要根据实际情况进行调整和完善。