用c语言按下列要求：1. 设计文件数据结构：设计文件的存储结构，将每个学生的学号、姓名、性别、年龄和总 绩点保存为一个记录，以便进行随机存取。例如：学号 12 个字节，姓名 8 个字节，性 别 2 个字节，年龄 2 个字节，总绩点 3 个字节，记起来一个学生的记录总共需要 27 个 字节，记录的长度就是 27 个字节 2. 根据所要保存的学生档案记录内容（学号、姓名、性别、年龄和总绩点），设计结构体 数据类型，结合结构体数组的运用实现文件记录的读写访问 3. 将以上各功能都设计成独立的函数，在 main 函数中显示一个菜单，让用户选择要执行 的功能，然后转而执行相应的函数编写程序

好的，我明白了你的问题。下面是一个简单的实现，你可以参考一下：

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

#define MAX_STUDENTS 100

struct student {
    char id[12];
    char name[8];
    char gender[2];
    int age;
    float score;
};

void add_student(struct student *students, int *count) {
    if (*count >= MAX_STUDENTS) {
        printf("Error: no more space for new students.\n");
        return;
    }

    struct student new_student;
    printf("Enter student ID: ");
    scanf("%s", new_student.id);
    printf("Enter student name: ");
    scanf("%s", new_student.name);
    printf("Enter student gender: ");
    scanf("%s", new_student.gender);
    printf("Enter student age: ");
    scanf("%d", &new_student.age);
    printf("Enter student score: ");
    scanf("%f", &new_student.score);

    students[*count] = new_student;
    *count += 1;

    printf("Student added successfully.\n");
}

void list_students(struct student *students, int count) {
    if (count == 0) {
        printf("No students found.\n");
        return;
    }

    printf("ID\tName\tGender\tAge\tScore\n");
    for (int i = 0; i < count; i++) {
        printf("%s\t%s\t%s\t%d\t%.2f\n", students[i].id, students[i].name, students[i].gender, students[i].age, students[i].score);
    }
}

void save_students(struct student *students, int count) {
    FILE *file = fopen("students.dat", "wb");
    if (file == NULL) {
        printf("Error: could not open file.\n");
        return;
    }

    fwrite(students, sizeof(struct student), count, file);
    fclose(file);

    printf("Students saved to file.\n");
}

void load_students(struct student *students, int *count) {
    FILE *file = fopen("students.dat", "rb");
    if (file == NULL) {
        printf("Error: could not open file.\n");
        return;
    }

    *count = 0;
    while (fread(&students[*count], sizeof(struct student), 1, file) == 1) {
        *count += 1;
    }

    fclose(file);

    printf("Students loaded from file.\n");
}

int main() {
    struct student students[MAX_STUDENTS];
    int count = 0;

    int choice = -1;
    while (choice != 0) {
        printf("1. Add student\n");
        printf("2. List students\n");
        printf("3. Save students\n");
        printf("4. Load students\n");
        printf("0. Exit\n");

        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_student(students, &count);
                break;
            case 2:
                list_students(students, count);
                break;
            case 3:
                save_students(students, count);
                break;
            case 4:
                load_students(students, &count);
                break;
            case 0:
                printf("Exiting program.\n");
                break;
            default:
                printf("Invalid choice.\n");
        }

        printf("\n");
    }

    return 0;
}

这个程序用了结构体来表示每个学生的档案记录，通过结构体数组来保存多个学生的记录。菜单提供了 4 个选项：添加学生、列出学生、保存学生到文件、从文件中加载学生数据。用户可以根据需要选择相应的功能。