实验4 继承

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);
}

 改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);
}

同名覆盖原则：派生类与基类中有相同成员时，若未强行指名，则通过派生类对象使用的是派生类的同名成员。

二元作用域分辨符：类名::成员的形式使用，，目的是为了访问基类中的同名函数。

类型兼容原则：指在需要基类对象的任何地方，都可以使用公有派生类的对象来替代。

battert.hpp

#ifndef BATTERY_H
#define BATTERY_H
#include <iostream>

using namespace std;
class Battery {
private:
    int capacity;
public:
    Battery(int capacity_0 = 70) :capacity(capacity_0) {
    }
    int get_capacity() {
        return capacity;
    }
};

#endif

car.hpp

#ifndef CAR_H
#define CAR_H
#include <iostream>
#include <string>

using namespace std;
class Car {
private:
    string maker;
    string model;
    int year;
    int odometers;
public:
    Car(string maker_0, string model_0, int year_0) :maker(maker_0), model(model_0), year(year_0) {
        odometers = 0;
    }
    void info() {
        cout << "maker:         " << maker << endl;
        cout << "model:         " << model << endl;
        cout << "year:          " << year << endl;
        cout << "odometers:     " << odometers << endl;
    }
    void update_odometers(int New_o) {
        if (New_o >= odometers)
            odometers = New_o;
        else
            cout << "行程更新数值有误" << endl;
    }
};
#endif

electricCar.hpp

#ifndef ELECTRICCAR_H
#define ELECTRICCAR_H
#include <iostream>
#include <string>
#include "battery.hpp"
#include "car.hpp"

using namespace std;
class ElectricCar :public Car {
private:
    Battery battery;
public:
    ElectricCar(string maker_0, string model_0, int year_0, int capacity_0 = 70) : Car(maker_0, model_0, year_0), battery(capacity_0) {
    }
    void info() {
        this->Car::info();
        cout << "capacity:      " << battery.get_capacity() << "-kWh" << endl;
    }

};
#endif

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(-1);
    oldcar.info();

    cout << endl;

    // test class of ElectricCar
    ElectricCar newcar("Tesla", "model s", 2016);
    newcar.update_odometers(500);
    cout << "\n--------newcar's info--------\n";
    newcar.info();
}

 pets.hpp

 

#ifndef PETS_H
#define PETS_H
#include <iostream>
#include <string>

using std::cout;
using std::string;
using std::endl;

class MachinePets {
private:
    string nickname;
public:
    MachinePets(const string name_0) :nickname(name_0) {
    }
    string get_nickname()const {
        return nickname;
    }
    virtual string talk() {
        return "hong hong~";
    }
};

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~";
    }
};
#endif

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);
}