Сохранить и прочитать структуру с бинарного файла С

[NikitaPND]

Мне нужно чтобы все записывалось в бинарный файл (предусмотреть, если его нет, и тогда сказать что база данных пуста). То есть, чтобы при первом запуске бд была пустая, человек заполнил структуру, она сохранилась в бинарный файл и при следуюзем запуске, когда человек захочет посмотреть список студентов он увидит данные о том студенте, данные о котором вводил в прошлый раз. Не пойму то-ли я как-то неправильно считываю, то-ли сохраняю в файл что-то не то. Помогите умоляю!:с

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

int isValidPositiveNaturalNumber2(const char* str) { // Check
    int r = 0;
    while (str[r] != '\0') {
        if (!isdigit(str[r]) || isalpha(str[r])) {
            return 0;
        }
        r++;
    }
    return 1;
}

typedef enum { // Enum
    MALE,
    FEMALE
} Gender;

typedef struct { // Struct
    int year;
    int month;
    int day;
} Date;

typedef struct Student { // Struct
    char *lastName;
    char *firstName;
    char *middleName;
    Date birthDate;
    char *group;
    Gender gender;
    struct Student* next;
} Student;

void freeStudentList(Student *students) { // Free list of students
    Student *current = students;
    while (current != NULL) {
        Student *temp = current;
        current = current->next;
        free(temp->lastName);
        free(temp->firstName);
        free(temp->middleName);
        free(temp->group);
        free(temp);
    }
}

void appendStudent(Student **head, Student *newStudent) { // Append student to the end of the list
    if (*head == NULL) {
        *head = newStudent;
    } else {
        Student *current = *head;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = newStudent;
    }
}

Student* createStudentNode(const char *lastName, const char *firstName, const char *middleName, Date birthDate, const char *group, Gender gender) { // Create a new student node
    Student *newStudent = (Student*)malloc(sizeof(Student));
    if (newStudent == NULL) {
        printf("Error: Failed to allocate memory for a new student\n");
        return NULL;
    }

    newStudent->lastName = strdup(lastName);
    newStudent->firstName = strdup(firstName);
    newStudent->middleName = strdup(middleName);
    newStudent->birthDate = birthDate;
    newStudent->group = strdup(group);
    newStudent->gender = gender;
    newStudent->next = NULL;

    return newStudent;
}

void printStudentList(Student *students) { // Print the list of students
    FILE *file = fopen("data.bin", "rb"); // Open file for reading in binary mode
    if (file == NULL) {
        printf("The list of students is empty.\n");
        return;
    }

    // Read data from the file
    Student *current = (Student*)malloc(sizeof(Student));
    if (current == NULL) {
        printf("Error: Failed to allocate memory for a student.\n");
        fclose(file);
        return;
    }

    size_t read = fread(current, sizeof(Student), 1, file);
    if (read != 1) {
        printf("The list of students is empty.\n");
        fclose(file);
        free(current);
        return;
    }

    printf("List of students:\n");
    while (!feof(file)) {
        printf("%s %s %s\n", current->lastName, current->firstName, current->group);
        read = fread(current, sizeof(Student), 1, file);
    }

    fclose(file);
    free(current);
}

void appendNewStudent(Student **head) { // Append a new student
    char lastName[50];
    char firstName[50];
    char middleName[50];
    char yearStr[20], monthStr[20], dayStr[20], genderChoiceStr[20];
    int year, month, day, genderChoice;
    char group[10];

    printf("Enter the student's last name: ");
    scanf("%s", lastName);
    printf("Enter the student's first name: ");
    scanf("%s", firstName);
    printf("Enter the student's middle name: ");
    scanf("%s", middleName);

    while (1) {
        printf("Enter the student's birth year: ");
        year = scanf("%s", yearStr);

        if (year != 1 || !isValidPositiveNaturalNumber2(yearStr)) {
            printf("Invalid input. Please enter a positive integer.\n");
            while (getchar() != '\n');
            continue;
        }

        year = atoi(yearStr);

        if (year < 1900 || year > 2024) {
            printf("The birth year should be between 1900 and 2024. Please try again.\n");
        } else {
            break;
        }
    }

    // Similar loops for month and day inputs

    printf("Enter the student's group: ");
    scanf("%s", group);

    // Similar loop for gender input

    Gender gender = genderChoice == 0 ? MALE : FEMALE;

    Date birthDate = {year, month, day};

    Student *newStudent = createStudentNode(lastName, firstName, middleName, birthDate, group, gender);
    if (newStudent == NULL) {
        printf("Error: Failed to add a new student.\n");
        return;
    }

    appendStudent(head, newStudent);

    // Get data from the file
    FILE *file = fopen("data.bin", "ab"); // Open file for appending in binary mode
    if (file == NULL) {
        printf("Error: Failed to open the file for writing.\n");
        return;
    }

    // Write data of the new student to the file
    size_t written = fwrite(newStudent, sizeof(Student), 1, file);
    if (written != 1) {
        printf("Error writing to the file.\n");
    } else {
        printf("The student has been successfully added to the list and written to the file.\n");
    }

    fclose(file);
}

void menu(Student *students) { // Main menu
    char userChoiceStr[20];
    int result;

    while (1) {
        result = scanf("%s", userChoiceStr);

        if (result != 1 || !isValidPositiveNaturalNumber2(userChoiceStr)) {
            printf("Invalid input. Please enter a positive integer.\n");
            while (getchar() != '\n');
            continue;
        }

        result = atoi(userChoiceStr);

        if (result == 4) {
            break;
        }

        switch (result) {
            case 1:
                printStudentList(students);
                break;

            case 2:
                appendNewStudent(&students);
                break;
        
            case 3:
                printf("sdfsd");
                break;

            default:
                printf("Invalid choice, please select again.\n");
                break;
        }
    }
}

int main() {
    Student* students = NULL; // Initialization

    menu(students);

    freeStudentList(students); // Cleanup

    return 0;
}