[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:1Circle area:3.14Triangle area:1.5
#include <iostream>#define PI 3.14using 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;  }