实验报告 13--1

#include <iostream>
using namespace std;

class Vehicle
{
public:
 void run() const { cout << "run a vehicle. "<<endl; } //(2) run()为虚函数
};

class Car: public Vehicle
{
public:
 void run() const {cout << "run a car. "<<endl;  }
};

class Airplane: public Vehicle
{
public:
 void run() const {cout << "run a airplane. "<<endl;}
};

int main()
{
 cout<<"(a) 直接用对象访问成员函数: "<<endl;
 Vehicle v;
 v.run();
 Car car;
 Airplane airplane;
 car.run();
 airplane.run();

 cout<<"(b) 用指向基类的指针访问成员函数: "<<endl;
 Vehicle *vp;
 vp=&car;
 vp->run();
 vp=&airplane;
 vp->run();
 system("pause");
 return 0;
}   

 

 

 

 

 

 

 

 

 

 

#include "iostream"
#include<string>
using namespace std;
class Animal
{
public:
 virtual void cry() {cout<<"不知哪种动物，让我如何学叫？"<<endl;}
};
class Mouse :public Animal
{
public:
 void cry() {cout<<"我叫Jerry，是一只老鼠，我的叫声是：吱吱吱！"<<endl;}
 Mouse(string Mouse_name);
private:
 string Mouse_name;
};
class Cat :public Animal
{
public:
 void cry() {cout<<"我叫Tom，是一只猫，我的叫声是：喵喵喵！"<<endl;}
 Cat(string Cat_name);
private:
 string Cat_name;
};
class Dog :public Animal
{
public:
 void cry() {cout<<"我叫Droopy，是一条狗，我的叫声是：汪汪汪！"<<endl;}
 Dog(string Dog_name);
private:
 string Dog_name;
};
class Giraffe :public Animal
{
public:
 void cry() {cout<<"我叫Gill，是长颈鹿，脖子太长，发不出声音来！"<<endl;}
 Giraffe(string Giraffe_name);
private:
 string Giraffe_name;
};

Mouse::Mouse(string Mouse_name)
{
 this->Mouse_name=Mouse_name;
}
Cat::Cat(string Cat_name)
{
 (*this).Cat_name=Cat_name;
}
Dog::Dog(string Dog_name)
{
 this->Dog_name=Dog_name;
}
Giraffe::Giraffe(string Giraffe_name)
{
 this->Giraffe_name=Giraffe_name;
}
int main( )
{
 Animal *p;
 p = new Animal(); p->cry(); //输出: 不知哪种动物，让我如何学叫？(问题出自此处)
 Mouse m("Jerry"); p=&m; p->cry(); //输出: 我叫Jerry，是一只老鼠，我的叫声是：吱吱吱！
 Cat c("Tom");  p=&c; p->cry(); //输出: 我叫Tom，是一只猫，我的叫声是：喵喵喵！
 Dog d("Droopy");  p=&d; p->cry(); //输出: 我叫Droopy，是一条狗，我的叫声是：汪汪汪！
 Giraffe g("Gill");  p=&g; p->cry(); //输出: 我叫Gill，是长颈鹿，脖子太长，发不出声音来！
 //delete p;
 system("pause");
 return 0;
}

 

 

 

 

 

#include<iostream>  
#include<Cmath>  
using namespace std;
const double pi=3.1415926; 
class Shape //定义抽象基类
{
public:
 virtual double areas()=0;
};
 
class Circle: public Shape   //利用抽象基类定义圆类  
{ 
public: 
    Circle(double Circle_radius);//构造函数  
    ~Circle(){}
 double areas();
private: 
    double Circle_radius; 
};

class Rectangle: public Shape    //利用抽象基类定义矩形类    
{ 
public: 
    Rectangle(double Rectangle_long,double Rectangle_wide);//构造函数  
 ~Rectangle(){} 
 double areas(); 
private: 
    double Rectangle_long; 
 double Rectangle_wide; 
};

class Triangle: public Shape  //利用抽象基类定义三角形类  
{ 
public: 
    Triangle(double Triangle_bottom,double Triangle_high); //构造函数  
 ~Triangle(){} 
    double areas();
private: 
    double Triangle_bottom;
 double Triangle_high; 
};
Circle::Circle(double Circle_radius)//构造函数
{
 this->Circle_radius=Circle_radius;
}
double Circle::areas()
{
return (pi*Circle_radius*Circle_radius);
}
Rectangle::Rectangle(double Rectangle_long,double Rectangle_wide)
{
 this->Rectangle_long=Rectangle_long;
 this->Rectangle_wide=Rectangle_wide;
}
double Rectangle::areas()
{
 return (Rectangle_long*Rectangle_long);
}
Triangle::Triangle(double Triangle_bottom,double Triangle_high)
{
 this->Triangle_bottom=Triangle_bottom;
 this->Triangle_high=Triangle_high;
}
double Triangle::areas()
{
 return (Triangle_bottom*Triangle_high/2);
}

int main()
{
 Circle c1(12.6),c2(4.9);    //建立Circle类对象c1,c2,参数为圆半径
 Rectangle r1(4.5,8.4),r2(5.0,2.5);       //建立Rectangle类对象r1,r2,参数为矩形长、宽
 Triangle t1(4.5,8.4),t2(3.4,2.8);    //建立Triangle类对象t1,t2，参数为三角形底边长与高
 Shape *pt[6]={&c1,&c2,&r1,&r2,&t1,&t2}; //定义基类指针数组pt，各元素指向一个派生类对象
 double areas=0.0;      //areas为总面积
 for(int i=0; i<6; i++)
 {
  areas=areas+pt[i]->areas();
 }
 cout<<"totol of all areas="<<areas<<endl;   //输出总面积
 system("pause");
 return 0;
}