C++ を使用して簡単なレンタカー管理システムを作成するにはどうすればよいですか?

class Car {
private:
    int carID;
    string brand;
    string model;
    double rentalPrice;
    bool isRented;

public:
    Car(int id, string b, string m, double price) {
        carID = id;
        brand = b;
        model = m;
        rentalPrice = price;
        isRented = false;
    }

    // getter and setter for carID, brand, model, rentalPrice, isRented
    
    void rentCar() {
        isRented = true;
    }
    
    void returnCar() {
        isRented = false;
    }
    
    double calculateRent(double numDays) {
        return rentalPrice * numDays;
    }
};

class CarRentalSystem {
private:
    vector<Car> cars;
    string adminUsername;
    string adminPassword;

public:
    CarRentalSystem(string username, string password) {
        adminUsername = username;
        adminPassword = password;
    }

    void addCar(int id, string brand, string model, double price) {
        Car newCar(id, brand, model, price);
        cars.push_back(newCar);
    }

    void rentCar(int id) {
        for (int i = 0; i < cars.size(); i++) {
            if (cars[i].getCarID() == id) {
                cars[i].rentCar();
                break;
            }
        }
    }

    void returnCar(int id) {
        for (int i = 0; i < cars.size(); i++) {
            if (cars[i].getCarID() == id) {
                cars[i].returnCar();
                break;
            }
        }
    }

    double calculateTotalRent(double numDays) {
        double totalRent = 0.0;
        for (int i = 0; i < cars.size(); i++) {
            if (cars[i].isRented()) {
                double rent = cars[i].calculateRent(numDays);
                totalRent += rent;
            }
        }
        return totalRent;
    }

    void displayAllCars() {
        for (int i = 0; i < cars.size(); i++) {
            // display car information
        }
    }
};

int main() {
    string username = "admin";
    string password = "password";
    CarRentalSystem system(username, password);
    
    // 添加车辆信息
    system.addCar(1, "Toyota", "Camry", 50.0);
    system.addCar(2, "Honda", "Accord", 60.0);
    system.addCar(3, "BMW", "X5", 100.0);
    
    // 租赁和归还车辆
    system.rentCar(1);
    system.rentCar(3);
    system.returnCar(1);
    
    // 统计租金
    double rent = system.calculateTotalRent(5);
    cout << "Total rent: $" << rent << endl;
    
    // 显示所有车辆信息
    system.displayAllCars();
}