ООП лаб 10(2)

#include <iostream>
#include <string>

using namespace std;

class transport {
protected:
    int number_wheels;
public:
    virtual void input() {
        cout << "Enter number of wheels: ";
        cin >> number_wheels;
    }
    virtual void print() {
        cout << "Number of wheels: " << number_wheels << endl;
    }
};

class electric_transport : transport {
    int battery_charge;
private:
    void input() {
        transport::input();
        cout << "Enter battery charge: ";
        cin >> battery_charge;
    }
    void print() {
        transport::print();
        cout << "Battery charge: " << battery_charge << endl;
    }

    friend istream& operator>> (istream&, electric_transport&);
    friend ostream& operator<< (ostream&, electric_transport&);
};


istream& operator>> (istream& in, electric_transport& e_t) {
    cout << "Enter number of wheels: ";
    in >> e_t.number_wheels;
    cout << "Enter battery charge: ";
    in >> e_t.battery_charge;

    return in;
}

ostream& operator<< (ostream& out, electric_transport& e_t) {
    out << "Enter number of wheels: " << e_t.number_wheels << endl;
    out << "Enter battery charge: " << e_t.battery_charge << endl;

    return out;
}

class railway_transport : transport {
    int number_carriage;
private:
    void input() {
        transport::input();
        cout << "Enter number of carriage: ";
        cin >> number_carriage;
    }
    void print() {
        transport::print();
        cout << "Number of carriage: " << number_carriage << endl;
    }

    friend istream& operator>> (istream&, railway_transport&);
    friend ostream& operator<< (ostream&, railway_transport&);
};

istream& operator>> (istream& in, railway_transport& r_t) {
    cout << "Enter number of wheels: ";
    in >> r_t.number_wheels;
    cout << "Enter number of carriage: ";
    in >> r_t.number_carriage;

    return in;
}

ostream& operator<< (ostream& out, railway_transport& r_t) {
    out << "Number of wheels: " << r_t.number_wheels << endl;
    out << "Number of carriage: " << r_t.number_carriage << endl;

    return out;
}

int main() {
    transport t;
    t.input();
    cout << endl;
    t.print();
    cout << endl;

    electric_transport e_t;
    cin >> e_t;
    cout << endl << e_t << endl;

    railway_transport r_t;
    cin >> r_t;
    cout << endl << r_t << endl;


    return 0;
}