Question

C++程序问题

将Shape基类定义为抽象类，其成员函数GetArea()为虚函数，由Shape类派生出Circle类（圆）和Rectangle类（矩形），并由Rectangle类派生出Square类（正方形），它们都利用GetArea()函数计算图形面积。根据下列调用语句，分别写出各个类的定义，并且成功地调试运行程序
下面是已经给出的主函数：
Shape *s[5];
s[0]=new Circle(2);
s[1]=new Circle(3);
s[2]=new Rectangle(3, 4);
s[3]=new Rectangle(4, 5);
s[4]=new Square(5);
for(int i=0; i<5; i++) cout<<s[i]->GetArea()<<endl;
整个程序怎么写啊

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Answer 1

#include<iostream>
#define PI 3.14
using namespace std;
class Shape
{
public:
virtual double GetArea()
{
return 0.0;
}
};
class Circle:public Shape
{
protected:
double r;
public:
Circle(double r)
{
this->r=r;
}
virtual double GetArea()
{
return PI*r*r;
}
};
class Rectangle:public Shape
{
protected:
double x,y;
public:
Rectangle(double x,double y)
{
this->x=x;
this->y=y;
}
virtual double GetArea()
{
return x*y;
}
};
class Square:public Rectangle
{
public:
Square(double x):Rectangle(x,x)
{

}
virtual double GetArea()
{
return x*y;
}
};
int main()
{

Shape *s[5];
s[0]=new Circle(2);
s[1]=new Circle(3);
s[2]=new Rectangle(3, 4);
s[3]=new Rectangle(4, 5);
s[4]=new Square(5);
for(int i=0; i<5; i++) cout<<s[i]->GetArea()<<endl;
}

追问

因为他的比较好理解，所以我采用它的了

追答

我提交的是候没有注意到已经有人提交了。

Answer 2

#include<iostream>
using namespace std;
class Shape
{
public:
//Shape();
virtual double GetArea()=0;
//virtual ~Shape();
};

class Circle: public Shape
{

private: double _r;
public:Circle(double a)
{
_r=a;
}

virtual double GetArea()
{
return 3.14*_r*_r;
}
// virtual ~Circle();
};

class Rectangle:public Shape
{

private: double _width;
double _height;
public:Rectangle(double width,double height)
{
_width=width;
_height=height;
}
Rectangle()
{
_width=0;
_height=0;
}

virtual double GetArea()
{
return _width*_height;
}
// virtual ~Rectangle();
};

class Square: public Rectangle
{

private: double _width;

public:Square(double width)
{
_width=width;

}

virtual double GetArea()
{
return _width*_width;
}
// virtual ~Square();
};

void main()
{
Shape *s[5];

s[0]=new Circle(2);
s[1]=new Circle(3);
s[2]=new Rectangle(3, 4);
s[3]=new Rectangle(4, 5);
s[4]=new Square(5);
for(int i=0; i<5; i++) cout<<s[i]->GetArea()<<endl;
}