c – 派生类析构函数如何被调用在以下程序中是私有的？

#include<iostream>

class base
{
   public:
       virtual ~base(){std::cout << "base\n";}
};
class derived : public base
{
   private:
        ~derived(){std::cout << "derived\n";} /* destructor is private */
};
int main()
{
      base *pt= new derived;
      delete pt;
}

上述程序编译并运行正常.
派生类析构函数如何被调用是私有的？

解决方法

这不仅会发生在析构函数中.

您可以使用私有功能覆盖任何虚拟公共功能.

#include<iostream>

class base
{
   public:
       virtual void x(){std::cout << "base\n";}
};
class derived : public base
{
   private:
        void x(){std::cout << "derived\n"; base::x();}
};
int main()
{
      base *pt= new derived;
      pt->x(); //OK
      //((derived *)pt)->x();  //error: ‘virtual void derived::x()’ is private
      derived *pt2= new derived;
      //pt2->x();  //error: ‘virtual void derived::x()’ is private
      ((base *)pt2)->x(); //OK
}

这个上升/下降是你必须使用指针到基础来访问这个方法.
此功能是将公共API与自定义实现分离的方法之一.

所以,换句话说,你的析构函数被调用,因为它在基地被声明为public,你通过指向base的指针来调用它.