8-16(

C++多态性程序例子

#include <iostream.h>

class A
{
public:
	virtual ~A() { cout<<"A::~A() called.\n"; }
};

class B : public A
{
public:
	B(int i) { buf = new char[i]; }
	virtual ~B()
	{
		delete [] buf;
		cout<<"B::~B() called.\n";
	}
private:
	char * buf;
};

void fun(A *a)
{
	delete a;     //使用delete时自动调用析构函数
}

void main()
{
	A *a = new B(15);
	fun(a);
}