#include <iostream>
#include <typeinfo>

// definitation of Graph
class Graph
{
public:
    void draw() { std::cout << "Graph::draw() : just as an interface\n"; }
};


// definition of Rectangle, derived from Graph
class Rectangle : public Graph
{
public:
    void draw() { std::cout << "Rectangle::draw(): programs of draw a rectangle\n"; }
};


// definition of Circle, derived from Graph
class Circle : public Graph
{
public:
    void draw() { std::cout << "Circle::draw(): programs of draw a circle\n"; }
};


// definitaion of fun(): as a call interface
void fun(Graph *ptr)
{
    std::cout << "pointer type: " << typeid(ptr).name() << "\n";
    std::cout << "RTTI type: " << typeid(*ptr).name() << "\n";
    ptr -> draw();
}

// test 
int main()
{
    Graph g1;
    Rectangle r1;
    Circle c1;

    // call by object name
    g1.draw();
    r1.draw();
    c1.draw();

    std::cout << "\n";

    // call by object name, and using the scope resolution operator::
    r1.Graph::draw();
    c1.Graph::draw();

    std::cout << "\n";

    // call by pointer to Base class
    fun(&g1);
    fun(&r1);
    fun(&c1);
}

 

 

 

在基类Graph的成员函数draw()前面加一个关键字virtual

#include <iostream>
#include <typeinfo>

// definitation of Graph
class Graph
{
public:
    virtual void draw() { std::cout << "Graph::draw() : just as an interface\n"; }
};


// definition of Rectangle, derived from Graph
class Rectangle : public Graph
{
public:
    void draw() { std::cout << "Rectangle::draw(): programs of draw a rectangle\n"; }
};


// definition of Circle, derived from Graph
class Circle : public Graph
{
public:
    void draw() { std::cout << "Circle::draw(): programs of draw a circle\n"; }
};


// definitaion of fun(): as a call interface
void fun(Graph *ptr)
{
    std::cout << "pointer type: " << typeid(ptr).name() << "\n";
    std::cout << "RTTI type: " << typeid(*ptr).name() << "\n";
    ptr -> draw();
}

// test 
int main()
{
    Graph g1;
    Rectangle r1;
    Circle c1;

    // call by object name
    g1.draw();
    r1.draw();
    c1.draw();

    std::cout << "\n";

    // call by object name, and using the scope resolution operator::
    r1.Graph::draw();
    c1.Graph::draw();

    std::cout << "\n";

    // call by pointer to Base class
    fun(&g1);
    fun(&r1);
    fun(&c1);
}

 

 

battery.hpp

#pragma once
#include<iostream>
using namespace std;

class Battery {
public:
    Battery(int capacity0 = 70) :capacity(capacity0) {};
    int get_capacity()
    {return capacity;}
private:
     int capacity;
};

car.hpp

#include<iostream>
#include<string>
using namespace std;

class Car {
public:
    Car(string maker0, string model0, int year0, int odometers0 = 0) :maker(maker0), model(model0), year(year0), odometers(odometers0) {};

    void info() {
        cout << "maker:\t\t" << maker << endl;
        cout << "model:\t\t" << model << endl;
        cout << "year:\t\t" << year << endl;
        cout << "odometers:\t" << odometers << endl;
    }
    
    void update_odometers(int odometers0)
    {
        if (odometers0 < odometers)
        {
            cout << "The update_odometers is wrong" << endl;
        }
        else
        {
            odometers = odometers0;
        }

    }
    
private:
    string maker;
    string model;
    int year;
    int odometers;
};

ElectricCar.hpp

#include"battery.hpp"
#include"car.hpp"
#include<iostream>
using namespace std;

class ElectricCar :public Car {
public:
    ElectricCar(string maker0, string model0, int year0, int odometers0 = 0, int battrey0 = 70) :Car(maker0, model0, year0, odometers0), battery(battrey0) {};
    

    void info()
    {
        Car::info();
        cout << "capacity:\t" << battery.get_capacity() << "-KWh" << endl;
    }
private:
    Battery battery;
};

 

task3.cpp

#include <iostream>
#include "electricCar.hpp"

int main()
{
    using namespace std;

    // test class of Car
    Car oldcar("Audi", "a4", 2016);
    cout << "--------oldcar's info--------" << endl;
    oldcar.update_odometers(25000);
    oldcar.info();

    cout << endl;

    // test class of ElectricCar
    ElectricCar newcar("Tesla", "model s", 2016);
    newcar.update_odometers(2500);
    cout << "\n--------newcar's info--------\n";
    newcar.info();
}

 

pets.hpp task4.cpp

#include<iostream>
#include<string>
using namespace std;
class MachinePets 
{
public:
    MachinePets(const string s) { nickname = s; }
    const string get_nickname() { return nickname; }
    virtual string  talk() { return "a"; }    ~MachinePets()=default;
private:
    string nickname;
};
class PetCats:public MachinePets
{
public:
    PetCats(const string c) :MachinePets(c){ }
    string talk() { return "miao wu~"; }    ~PetCats()=default;
};
class PetDogs:public MachinePets
{
public:
    PetDogs(const string s):MachinePets(s){}
    string talk() { return "wang wang~"; }    ~PetDogs()=default;
};

void play(MachinePets *ptr)
{
    std::cout << ptr->get_nickname() << " says " << ptr->talk() << std::endl;
}

int main()
{
    PetCats cat("miku");
    PetDogs dog("da huang");

    play(&cat);
    play(&dog);
}