虚析构函数

#include <iostream>
using namespace std;
class A{
  public:
    virtual ~A( ){
    cout<<"A::~A( ) called "<<endl; }
 };
class B:public A{
  char *buf;
  public:
    B(int i) { buf=new char[i]; }
    virtual ~B( ){
    delete []buf;
    cout<<"B::~B( ) called"<<endl;
 }
};
void fun(A *a) {
   delete a;
}
int main( )
 { A *a=new B(10);
   fun(a);
 }

先析构派生类，在析构基类，如不是虚析构函数，仅会析构基类