实验4 继承

#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);
}

 

#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);
}

 1.同名覆盖原则：

    当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中的同名成员。 如要通过派生类对象访问基类中被覆盖的同名成员,应使用基类名限定。

2.二元作用域分辨符：

    可以通过类型名::的方式区分将要调用的函数究竟属于哪一类。

3.类型兼容原则：

    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。

    派生类的对象可以隐含转换为基类的对象。

    派生类的对象可以初始化基类的引用。

    派生类的指针可以隐含转换为基类的指针。

    在替代后，派生类对象可以作为基类的对象使用，但只能使用从基类继续的成员。

# ifndef BATTERY_H
# define BATTERY_H
# include <iostream>
using namespace std;
class Battery {
private:
    int capacity;
public:
    Battery(int a=70):capacity(70) {}
    int get_capacity(){
        return capacity;
    }

};
#endif

# ifndef CAR_H
# define CAR_H
# include <iostream>
using namespace std;
class Car {
private:
    string maker;
    string model;
    int year;
    int odometers;
public:
    Car(string a="XXXXX",string b="XXXXX",int c=2000,int d=0):maker(a),model(b),year(c),odometers(d) {}
    void info() {
        cout << "maker:      " << maker << endl;
        cout << "model:      " << model << endl;
        cout << "year:       " << year << endl;
        cout << "odometers:  " << odometers << endl;
    }
    void update_odometers(int a) {
        if (a >= odometers)
            odometers = a;
        else
            cout << "Error updating value" << endl;
    }
};
#endif

# ifndef ELECTRICCAR_H
# define ELECTRICCAR_H
# include <iostream>
# include "car.hpp"
# include "battery.hpp"
using namespace std;
class ElectricCar :public Car {
private:
    Battery battery;
public:
    ElectricCar(string a="XXXXX",string b="XXXXX",int c=2000,int d=70,int e=0):Car(a,b,c,e),battery(d){}
    void info() {
        Car::info();
        cout << "capacity:   " <<battery.get_capacity() <<"-kWh"<<endl;
    }
};
#endif

#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(85000);
    oldcar.info();

    cout << endl;

    // test class of ElectricCar
    ElectricCar newcar("Tesla", "model s", 2016);
    newcar.update_odometers(7800);
    cout << "\n--------newcar's info--------\n";
    newcar.info();
}

 

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

#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);
}