Student Data Management in C++

#include <iostream>
#include <fstream>
#include <vector>

class Student {
public:
    std::string name;
    int rollNumber;
    double grade;

    // Constructor to initialize student data
    Student(std::string n, int roll, double g) : name(n), rollNumber(roll), grade(g) {}

    // Display student information
    void display() {
        std::cout << "Name: " << name << std::endl;
        std::cout << "Roll Number: " << rollNumber << std::endl;
        std::cout << "Grade: " << grade << std::endl;
    }
};

// Function to add a new student to the database
void addStudent(std::vector<Student>& students) {
    std::string name;
    int rollNumber;
    double grade;

    std::cout << "Enter student name: ";
    std::cin >> name;
    std::cout << "Enter roll number: ";
    std::cin >> rollNumber;
    std::cout << "Enter grade: ";
    std::cin >> grade;

    students.emplace_back(name, rollNumber, grade);
}

// Function to display all student data
void displayAllStudents(const std::vector<Student>& students) {
    std::cout << "Student Data:" << std::endl;
    for (const Student& student : students) {
        student.display();
        std::cout << std::endl;
    }
}

// Function to save student data to a file
void saveStudentData(const std::vector<Student>& students, const std::string& filename) {
    std::ofstream file(filename);
    if (!file.is_open()) {
        std::cerr << "Error opening file for writing." << std::endl;
        return;
    }

    for (const Student& student : students) {
        file << student.name << " " << student.rollNumber << " " << student.grade << std::endl;
    }

    file.close();
    std::cout << "Student data saved to " << filename << std::endl;
}

int main() {
    std::vector<Student> students;
    std::string filename = "student_data.txt";

    // Load student data from a file (if available)
    std::ifstream file(filename);
    if (file.is_open()) {
        std::string name;
        int rollNumber;
        double grade;

        while (file >> name >> rollNumber >> grade) {
            students.emplace_back(name, rollNumber, grade);
        }

        file.close();
    }

    int choice;
    do {
        std::cout << "Student Data Management System" << std::endl;
        std::cout << "1. Add Student" << std::endl;
        std::cout << "2. Display All Students" << std::endl;
        std::cout << "3. Save Student Data" << std::endl;
        std::cout << "4. Quit" << std::endl;
        std::cout << "Enter your choice: ";
        std::cin >> choice;

        switch (choice) {
            case 1:
                addStudent(students);
                break;
            case 2:
                displayAllStudents(students);
                break;
            case 3:
                saveStudentData(students, filename);
                break;
            case 4:
                std::cout << "Exiting the program." << std::endl;
                break;
            default:
                std::cout << "Invalid choice. Please try again." << std::endl;
        }

    } while (choice != 4);

    return 0;
}