派生类的成员函数是否从基类继承虚拟？ [英] Does derived class' member functions inherit virtualness from base class?

问题描述

假设我们有以下两个类，A是具有虚拟析构函数的基类，B是其析构函数没有'virtual'限定符的派生类。我的问题是，如果我从B得到更多的类，将B的析构函数自动继承虚拟或我需要显式地将'virtual'之前'〜B（）{... }'

  class A 
 {
 public：
 A {std :: cout< create A<< std :: endl;}; 
 virtual〜A（）{std :: cout<< destroy A<< std :: endl;}; 
}; 
 
 B类：A 
 {
 public：
 B（）{std :: cout< create B<< std :: endl;}; 
〜B（）{std :: cout<< 破坏B< std :: endl;}; 
}; 
  
 
 
解决方案
从C ++标准> 
 
 
 
 
如果在 Base中声明了一个虚拟成员函数 vf  ，直接或间接从中派生和
a类派生 em> [...]  
，然后 Derived :: vf 也是虚拟的（无论是否声明）。
 
 
是的。
 
Say we have the following two classes, A is the base class with virtual destructor and B is the derived class whose destructor doesn't have 'virtual' qualifier. My question is, if I going to derive more classes from B, will B's destructor automatically inherit the virtualness or I need to explicitly put 'virtual' before '~B() {...}'
class A
{
public:
    A() { std::cout << "create A" << std::endl;};
    virtual ~A() { std::cout << "destroy A" << std::endl;};
};

class B: A
{
public:
    B() { std::cout << "create B" << std::endl;};
    ~B() { std::cout << "destroy B" << std::endl;};
};

解决方案
From C++ standard (section 10.3):

  
If a virtual member function vf is declared in a class Base and in
  a class Derived, derived directly or indirectly from Base, [...]
  then Derived::vf is also virtual (whether or not it is so declared).
So yes.

                        
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