实验四 继承

实验任务2:

修改前task2.cpp:

#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);
}

运行测试截图:

 

 

 修改后task2.cpp:

#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);
}

运行测试截图:

 

 

 

实验任务3:

battery.hpp:

public:Battery(string capa="70-kWh"):capacity(capa){};
public:
    string getCapacity(){
        return capacity;
    }
private:
    string capacity;
};

car.hpp:

#include <string>
using namespace std;
class Car{
public:
    Car(string Maker,string Model,int Year):maker(Maker),model(Model),year(Year){
        odometers=0;
    };
    void info(){
        cout<<"maker:"<<"         "<<maker<<endl;
        cout<<"model:"<<"         "<<model<<endl;
        cout<<"year:"<<"          "<<year<<endl;
        cout<<"odometers:"<<"     "<<odometers;

    }
    void update_odometers(int new_odometers){
        if(new_odometers<odometers){
            cout<<"修改里程数失败！更新后里程数小于当前里程数";
            return;
        }
        else{
            odometers=new_odometers;
        }

    }

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

electricCar.hpp:

#include "car.hpp"
#include "battery.hpp"
class ElectricCar: public Car{
public:
    ElectricCar(string Maker,string Model,int Year):Car(Maker,Model,Year){
        odometers=0;
    };
    void info(){
        cout<<"maker:"<<"         "<<maker<<endl;
        cout<<"model:"<<"         "<<model<<endl;
        cout<<"year:"<<"          "<<year<<endl;
        cout<<"odometers:"<<"     "<<odometers<<endl;
        cout<<"capacity:"<<"      "<<battery.getCapacity();
    }
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();
}

运行结果: 

 

 

实验任务4:

pets.hpp:

#include <string>
using namespace std;

class MachinePets{
public:
    MachinePets(string s):nickname(s){};
    virtual string talk(){ return "";};
    string get_nickname(){
        return nickname;
    }
protected:
    string nickname;

};


class PetCats: public MachinePets{
public:
    PetCats(const string s):MachinePets(s){};
    string talk(){
        return "miao wu~";
    };
};


class PetDogs : public MachinePets{
public:
    PetDogs(const string s):MachinePets(s){};
    string talk(){
        return "wang wang~";
    }
};

task4.cpp:

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

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);
}

运行测试截图: