用C++设计一个不能被继承的类

//题目：用C++设计一个不能被继承的类
#include<iostream>
#include<stdlib.h>
using namespace std;

class A
{
public:
static A* Construct(int n)
{
A* pa = new A;
pa->num = n;
return pa;
}
static void Desturct(A* pIntance)
{
delete pIntance;
pIntance = NULL;
}
private:
A(){}
~A(){}
public:
int num;
};
template <typename T>
class Base
{
friend T;
private:
Base(){}
~Base(){}
};

class Finalclass : virtual public Base < Finalclass >
{
public:
Finalclass(){}
~Finalclass(){}
};
int main()
{
A *f = A::Construct(9);
cout << f->num << endl;
A::Desturct(f);
Finalclass *p = new Finalclass;//堆上对象
Finalclass fs;//栈上对象

system("pause");
}