// 純虛函數的使用
#include  <iostream >
using namespace std;

const double PI = 3.14159;

class  CShape //定義一個抽象類
{
public:
	virtual float area() = 0;		//聲明為純虛函數
	virtual void print() = 0;		//聲明為純虛函數
};

class  CCircle:  public  CShape
{
public:
	CCircle( float r ): m_rad(r) {}
	float  area() { return PI * m_rad * m_rad; }
	void print()
	{
		cout << " 圓的面積是：" <<area() << endl;
	}
private:
	float	m_rad;		//圓的半徑
};

class  CRectangle: public  CShape  
{
public:
	CRectangle( float w, float h ): m_wid(w), m_hig(h) {}  
	float  area() { return m_wid *  m_hig; }
	void print()
	{
		cout << " 矩形的面積是："<< area() << endl;
	} 
private:
	float	m_wid, m_hig;		//矩形的長和寬
};

int main()
{
	CShape *layoutptr[2];					//定義一個基類類型的指針數組
	layoutptr[0] = new CCircle(3);			//可以讓基類類型的指針指向派生類對象
	layoutptr[1] = new CRectangle(2,4);	//可以讓基類類型的指針指向派生類對象
	for(int i=0;i<2;i++)
	{
		layoutptr[i]->print();
		delete layoutptr[i];			// 釋放占用的資源
	}

	return 0;
}