使用基类指针创建对象时缺少派生类析构函数

Question

在以下代码示例中，未调用派生类析构函数。知道为什么吗？ 我有一个具有虚函数的基类。现在我使用基类指针来创建派生类的新对象。我的理解是当派生类对象被销毁时，派生类的析构函数首先被调用，然后是基类。但是我只看到基类的析构函数被调用。有谁知道我做错了什么或者我对 c++ 的理解不正确？

#include <iostream>
#include <bitset>
using namespace std; 

class DomesticAnimals 
{
    public:
        DomesticAnimals() {
            cout <<"Domestic Animal Base" <<endl;
        }; 
        ~DomesticAnimals() {
            cout <<"Domestic Animal kill " <<endl;
        }; 
        virtual void Speak() = 0;
        virtual void EatFood()= 0; 
        virtual int NoOfLegs() {
            return 4; 
        } ;
};


class Cat : public DomesticAnimals
{
    public:
        Cat(); 
        ~Cat(); 
        void Speak() override; 
        void EatFood() override; 
};

Cat::Cat()
{
    cout << "Kat was born" << endl;
}

Cat:: ~Cat()
{
    cout << "Kill de Cat" << endl; 
}
void Cat:: Speak()
{
    cout << "Meow Meow " << endl; 
}

void Cat::EatFood()
{
    cout <<"Kat eet de muis vandaag !! " <<endl; 
}


class Dog : public DomesticAnimals
{
    public:
        Dog();
        ~Dog();
        void Speak() override; 
        void EatFood() override; 
};

Dog::Dog()
{
    cout << "A puppy was born" << endl; 
}

Dog::~Dog()
{
    cout << "Kill de hond" << endl; 
}

void Dog :: Speak()
{
    cout <<"bow bow woof woof" <<endl;
}

void Dog :: EatFood()
{
    cout << "de hond eet een kip voor middageten" <<endl;
}

void DogActions()
{
    DomesticAnimals* dog = new Dog;
    cout<< endl;
    dog->Speak(); 
    dog->EatFood();
    cout<<"No of legs for dog = "<< dog->NoOfLegs() <<endl; 
    cout<<endl;
    delete dog; 
    dog = NULL;
}

void CatActions()
{
    DomesticAnimals* cat = new Cat; 
    cat->Speak(); 
    cat->EatFood(); 
    cout<<"No of legs for cat = "<< cat->NoOfLegs() << endl;
    delete cat; 
    cat = NULL; 
}

int main(void)
{
    DogActions();
    CatActions();
    return 0;
}

程序的输出如下

Domestic Animal Base
A puppy was born

bow bow woof woof
de hond eet een kip voor middageten
No of legs for dog = 4

Domestic Animal kill 
Domestic Animal Base
Kat was born
Meow Meow 
Kat eet de muis vandaag !! 
No of legs for cat = 4
Domestic Animal kill 

Answer 1

基类的析构函数需要是虚拟的：

virtual ~DomesticAnimals() {
    cout << "Domestic Animal kill" << endl;
};

为了避免任何混淆（参见 cmets）：只有在通过指向其基类的指针删除对象的情况下才需要使析构函数为虚拟。这通常是需要多态性的情况。