c++继承与派生

#include <iostream>
using namespace std;
class vehicle
{
private:
    float weight;
    int wheels;
public:
    vehicle(int in_wheels,float in_weight)
    {
        wheels=in_wheels;
        weight=in_weight;
    }
    int get_wheels()
    {
        return wheels;
    }
    float get_weight()
    {
        return weight;
    }

};
class car:public vehicle
{
private:
    int passenger_load;
public:
    car(int in_wheels,float in_weight,int people=5):vehicle(in_wheels,in_weight)
    {
        passenger_load=people;
    }
    int get_passenger()
    {
        return passenger_load;
    }
};
int main()
{
    car bm(4,100);
    cout<<bm.get_wheels()<<endl;
    cout<<bm.get_weight()<<endl;
    cout<<bm.get_passenger()<<endl;
    return 0;
}

#include <iostream>
using namespace std;
class vehicle
{
private:
    float weight;
    int wheels;
public:
    vehicle(int in_wheels,float in_weight)
    {
        wheels=in_wheels;
        weight=in_weight;
    }
    int get_wheels()
    {
        return wheels;
    }
    float get_weight()
    {
        return weight;
    }

};
class car:private vehicle
{
private:
    int passenger_load;
public:
    car(int in_wheels,float in_weight,int people=5):vehicle(in_wheels,in_weight)
    {
        passenger_load=people;
    }
    int get_passenger()
    {
        return passenger_load;
    }
    int get_wheels()
    {
        return vehicle::get_wheels();
    }
    int get_weight()
    {
        return vehicle::get_weight();
    }
};
int main()
{
    car bm(4,100);
    cout<<bm.get_wheels()<<endl;
    cout<<bm.get_weight()<<endl;
    cout<<bm.get_passenger()<<endl;
    return 0;
}

#include <iostream>
using namespace std;
class vehicle
{
private:
    int wheels;
protected:
    float weight;
public:
    vehicle(int in_wheels,float in_weight)
    {
        wheels=in_wheels;
        weight=in_weight;
    }
    int get_wheels()
    {
        return wheels;
    }
    float get_weight()
    {
        return weight;
    }

};
class car:protected vehicle
{
private:
    int passenger_load;
public:
    car(int in_wheels,float in_weight,int people=5):vehicle(in_wheels,in_weight)
    {
        passenger_load=people;
    }
    int get_passenger()
    {
        return passenger_load;
    }
    int get_wheels()
    {
        return vehicle::get_wheels();
    }
    int get_weight()
    {
        return weight;
    }
};
int main()
{
    car bm(4,100);
    cout<<bm.get_wheels()<<endl;
    cout<<bm.get_weight()<<endl;
    cout<<bm.get_passenger()<<endl;
    return 0;
}