[YTU]_2921( Shape系列-7)

Description

小强做的Shape类在本次的测试中出了点状况，发现原来是其中的area函数的问题，请大家根据题意，帮助小强完成改动后的Shape类。

小强写的各种类

class Rectangle:public Shape
{
public:
 Rectangle(int c,double w,double h);
 double getwidth();
 double getheight();
 double area();
 double price();
protected:
 double height;
 double width;
};
Rectangle::Rectangle(int c,double w,double h):Shape(c)
{
 width=w;
 height=h;
}
double Rectangle::getwidth()
{
 return width;
}
double Rectangle::getheight()
{
 return height;
}
double Rectangle::area()
{
 return height*width;
}
double Rectangle::price()
{
 return height*width*color;
}  
class Circle:public Shape
{
public:
 Circle(int c,double r);
 double getradius();
 double area();
 double price();
protected:
 double radius;
};  
Circle::Circle(int c,double r):Shape(c)
{
 radius=r;
}
double Circle::getradius()
{
 return radius;
}
double Circle::area()
{
 return PI*radius*radius;
}
double Circle::price()
{
 return PI*radius*radius*color;
}
class Triangle:  public Shape
{
public:
 Triangle(int c,double b,double h);
 double area();
protected:
 double base,height;
};
Triangle::Triangle(int c,double b,double h):Shape(c)
{
 base=b;height=h;
}
double Triangle::area()
{
 return 0.5*base*height;
}
int main()
{
 Shape *pt[3];
 Rectangle rr(1,1,1);
 Circle cc(2,1);
 Triangle tt(2,1,3);
 pt[0]=&rr;
 pt[1]=&cc;
 pt[2]=&tt;
 cout<<"Rectangle area:"<<pt[0]->area()<<endl;
 cout<<"Circle area:"<<pt[1]->area()<<endl;
 cout<<"Triangle area:"<<pt[2]->area()<<endl;
return 0; 
}

提示：不用提交全部程序，只提交补充部分（包括头文件和π的定义）。

Input

无

Output

小强测试的各个类面积的数据

Sample Output

Rectangle area:1
Circle area:3.14
Triangle area:1.5
#include <iostream>
#define PI 3.14
using namespace std;
class Shape
{
public:
    Shape(int c);
    virtual double area()=0;
protected:
    double color;
};
Shape::Shape(int c){color=c;}
class Rectangle:public Shape 
{ 
public: 
 Rectangle(int c,double w,double h); 
 double getwidth(); 
 double getheight(); 
 double area(); 
 double price(); 
protected: 
 double height; 
 double width; 
}; 
Rectangle::Rectangle(int c,double w,double h):Shape(c) 
{ 
 width=w; 
 height=h; 
} 
double Rectangle::getwidth() 
{ 
 return width; 
} 
double Rectangle::getheight() 
{ 
 return height; 
} 
double Rectangle::area() 
{ 
 return height*width; 
} 
double Rectangle::price() 
{ 
 return height*width*color; 
} 
   
   
   
   
class Circle:public Shape 
{ 
public: 
 Circle(int c,double r); 
 double getradius(); 
 double area(); 
 double price(); 
protected: 
 double radius; 
}; 
   
Circle::Circle(int c,double r):Shape(c) 
{ 
 radius=r; 
} 
double Circle::getradius() 
{ 
 return radius; 
} 
   
double Circle::area() 
{ 
 return PI*radius*radius; 
} 
double Circle::price() 
{ 
 return PI*radius*radius*color; 
} 
 
class Triangle:  public Shape
{
public:
 Triangle(int c,double b,double h);
 double area();
protected:
 double base,height;
};
Triangle::Triangle(int c,double b,double h):Shape(c)
{
 base=b;height=h;
}
double Triangle::area()
{
    return 0.5*base*height;
}
 
int main() 
{ 
    Shape *pt[3];
    Rectangle rr(1,1,1);
    Circle cc(2,1);
    Triangle tt(2,1,3);
    pt[0]=&rr;
    pt[1]=&cc;
    pt[2]=&tt;
    cout<<"Rectangle area:"<<pt[0]->area()<<endl;
    cout<<"Circle area:"<<pt[1]->area()<<endl;
    cout<<"Triangle area:"<<pt[2]->area()<<endl;
return 0;  
}