When is a virtual extinction used?

The virtual extinction is useful when base class pointer points to the derived class instance and delete.

class Base{
public:
    ~Base() {
        cout << "Base destructor!" << endl;
    }
};

class Derived : public Base{
public:
    char* largeBuffer;
    Derived() {
        largeBuffer = new char[3000];
    }

    ~Derived() {
        cout << "Derived destructor!" << endl;
        delete[] largeBuffer;
    }
};

The above code did not set the extinction of base to virtual. In this situation, do the following codes 1 and 2 do the same thing?

int main(){
    //Code1
    cout << "---Derived* der1 = new Derived()---" << endl;
    Derived* der1 = new Derived();
    delete der1;

    //Code2
    cout << "\n\n---Base* der2 = new Derived()---" << endl;
    Base* der2 = new Derived();
    delete der2;

}

Results)

---Derived* der1 = new Derived()---
Derived destructor!
Base destructor!


---Base* der2 = new Derived()---
Base destructor!

In the case of Code 1, as you said, the extinction of Driven class will call the extinction of Base Class on its own. That's why the buffer was successfully deleted.

However, Derived destructor was not called in the case of code 2. The buffer will not be delete and will remain somewhere. The Base pointer points to an instance of the Derived class This is because members of Derived are not accessible

The virtual destructor is used to prevent memory from leaking in this situation.

class Base{
public:
    virtual ~Base() {
        cout << "Base destructor!" << endl;
    }
};

If Base extinction is set to virtual, Now, even in the case of Code 2, the extinction of Derived class is called Memory is released normally.