虚析构函数，派生类调用基类构造方法

#include <iostream>
using namespace std;

class A{

public:
	A()
	{
		cout<<"construct A"<<endl;
	}

	A(int a)
	{
		cout<<"construct int A"<<endl;
	}

	virtual ~A()  //析构函数 必须 声明为 虚函数，才能彻底释放内存空间
	{
		cout<<"destory A"<<endl;
	}

};

class B : public A{

public:
	B()
	{
		cout<<"construct B"<<endl;
	}

	B(int a):A(a)  //构造器调用A中int构造方法
	{
		cout<<"construct int B"<<endl;
	}
	
	~B()
	{
		cout<<"destory B"<<endl;
	}

};

class C:public B{

public:

	C()
	{
		cout<<"construct C"<<endl;
	}

	~C()
	{
		cout<<"destory C"<<endl;
	}

};


int main()
{
	A *p = new C();

	delete p;


	return 0;
}