实验四 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);
}

同名覆盖原则 :当调用派生类内与基类同名的函数时，默认调用派生类内的函数。二元作用域分辨符派生类名.基类::函数名，此时调用的是作用域标定的类内函数。类型兼容原则：当派生类与基类为public派生时，可以互相调用彼此类内的函数及数据。

 Graph::draw()变为虚基类，指针指向不再由指针类型决定，而是指向定义时的定义类型。于是r1指向的是Rectangle类，调用draw()时默认调用Rectangle::draw()；同理c1。

 

 

#include<iostream>
#include<string>
using namespace std;
class Battery {
public:
    Battery(int a= 70) :capacity(a) {}//具有默认形参数的构造函数
    int get_capacity() { return capacity; }
private:
    int capacity;//车在动力电池容量
};

#include<iostream>
#include<string>
using namespace std;
class Car {
private:
    string maker;//制造商
    string model;//型号
    int year;//生产年份
    int odometers;//行车里程数
public:
 //带参数的默认构造函数
    Car(string maker1, string model1, int year1, int odometers1 = 0) :maker(maker1), model(model1), year(year1), odometers(odometers1) {}
 //显示车辆信息 
    void info()
    {
        cout << "maker:" << maker << endl 
            << "model:" << model << endl 
            << "year:" << year << endl 
            << "odometers:" << odometers << endl;
    }
//更新行车里程数
    void update_odometers(int new_odometers)
    {
        if (new_odometers >= odometers)//合理
            odometers = new_odometers;
        else//不合理 警告
            cout << "New_odometers Error!" << endl;
    }
};

#include<iostream>
#include<string>
using namespace std;
class Car {
private:
    string maker;//制造商
    string model;//型号
    int year;//生产年份
    int odometers;//行车里程数
public:
 //带参数的默认构造函数
    Car(string maker1, string model1, int year1, int odometers1 = 0) :maker(maker1), model(model1), year(year1), odometers(odometers1) {}
 //显示车辆信息 
    void info()
    {
        cout << "maker:" << maker << endl 
            << "model:" << model << endl 
            << "year:" << year << endl 
            << "odometers:" << odometers << endl;
    }
//更新行车里程数
    void update_odometers(int new_odometers)
    {
        if (new_odometers >= odometers)//合理
            odometers = new_odometers;
        else//不合理 警告
            cout << "New_odometers Error!" << endl;
    }
};

#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();
}

 

#include<iostream>
#include<string>
using namespace std;
class MachinePets {
public:
    MachinePets(const string s) :nickname(s) {}//带参数的构造函数
    string get_nickname()const { return nickname; }
    virtual string talk() { return "0"; }
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~"; }
};

#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);
}