实验四 继承

实验任务4

pets.hpp:

#ifndef PETS_HPP
#define PETS_HPP
using namespace std;
#include<iostream>
#include<string>
class MachinePets
{
public:
    MachinePets() {};
    MachinePets(const string s)
    {
        nickname = s;
    }
    string get_nickname()
    {
        return nickname;
    }
    virtual string talk()
    {
        return "";
    }
    void machinepets(const string s)
    {
        nickname = s;
    }
private:
    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";
    }
};


#endif PETS_HPP

task4.hpp:

#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);
}

运行结果

 

 实验任务3

battery.hpp:

#ifndef BATTERY_HPP
#define BATTERY_HPP
using namespace std;
class Battery
{
public:
    Battery(double capa = 70) :capacity(capa) {};
    double get_capacity()
    {
        return capacity;
    }
private:
    double capacity;
};

#endif BATTERY_HPP

car.hpp:

#ifndef CAR_HPP
#define CAR_HPP
#include<string>
#include<iostream>
using namespace std;
class Car
{
public:
    Car() {}
    Car(string ma, string mo, int ye, double od = 0) :maker(ma), model(mo), year(ye), odometers(od) {}
    void info()
    {
        cout << "maker:           " << maker << endl;
        cout << "model:           " << model << endl;
        cout << "year:            " << year << endl;
        cout << "odometers:       " << odometers << endl;
    }
    void update_odometers(double a)
    {
        if (a < odometers)
        {
            cout << "wrong update" << endl;
        }
        else
        {
            odometers = a;
        }
    }
    string get_maker()
    {
        return maker;
    }
    string get_model()
    {
        return model;
    }
    int get_year()
    {
        return year;
    }
    double get_odometers()
    {
        return odometers;
    }
    void car(string ma, string mo, int ye)
    {
        maker = ma;
        model = mo;
        year = ye;
    }
private:
    string maker;
    string model;
    int year;
    double odometers;
};
#endif CAR_HPP

electriccar.hpp:

#include"car.hpp"
#include"battery.hpp"
#ifndef ELECTRICCAAR_HPP
#define ELECTRICCAAR_HPP
#include<iostream>
using namespace std;
class ElectricCar :public Car
{
public:
    ElectricCar(string ma, string mo, int ye)
    {
        car(ma, mo, ye);
    }
    void info()
    {
        cout << "maker:           " << get_maker() << endl;
        cout << "model:           " << get_model() << endl;
        cout << "year:            " << get_year() << endl;
        cout << "odometers:       " << get_odometers() << endl;
        cout << "capacity:        " << battery.get_capacity() << "-kWh" << endl;
    }
private:
    Battery battery;
};
#endif ELECTRICCAAR_HPP

task3.hpp:

#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2

源码：

#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 arectangle\n"; }
};
// definition of Circle, derived from Graph
class Circle : public Graph
{
public:
void draw() {
    std::cout << "Circle::draw(): programs of draw acircle\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：派生类和继承类函数完全相同时，通过派生类对象只访问派生类中的函数。

二元作用域分辨符：可以指定想要访问某个类的函数。

类型兼容原则：派生类对象可以作为基类的对象使用。