C++ 虛解構函式簡單測試

class Base {
public:
    virtual ~Base() { cout << "~Base" << '\n'; }
};

class Derived : public Base {
public:
    ~Derived() { cout << "~Derived" << '\n'; }
};

int main()
{
    {
        Base* b = new Derived;
        delete b;
    }

    system("pause");
    return EXIT_SUCCESS;
}

析構順序輸出：

~Derived
~Base

如果，把基類的解構函式設定成純虛擬函式，也必須要定義，不然編譯不過，只定義派生類的函式時不行的。
將解構函式設定成純虛，目的可能是不能讓類例項的作用。

class Base
{
public:
    virtual ~Base() = 0;
};

Base::~Base() { cout << "~Base" << '\n'; } // 必須要定義，不然編譯不過。

class Derived : public Base
{
public:
    ~Derived() { cout << "~Derived" << '\n'; }
};

輸出：

~Derived
~Base