ex_virtualfunc.cpp

郑阿齐VC教材

#include <iostream.h>
class CShape
{
public:
	virtual float area()	// 将area定义成虚函数
	{ 	
		return 0.0;
	}							
};
class CTriangle:public CShape
{
public:
	CTriangle(float h, float w)	
	{ 	
		H=h;	W=w;	
	}
	float area()
	{	
		return (float)(H * W * 0.5);		
	}
private:
	float H, W;
};
class CCircle:public CShape
{
public:
	CCircle(float r)	
	{	R=r;		}
	float area()
	{	
		return (float)(3.14159265 * R * R);		
	}
private:
	float R;
};
void main()
{
	CShape *s[2];
	s[0] = new CTriangle(3,4);
	cout<<s[0]->area()<<endl;
	s[1] = new CCircle(5);
	cout<<s[1]->area()<<endl;
}