析構函數爲虛函數的必要性

在實現多態時，當用基類操作派生類，在析構時防止只析構基類而不析構派生類的狀況發生。

class Base {

Base(){}

~Base(){cout<<"Base::~Base()"<<endl;}

virtual void Work(){cout<<"Base::Work"<<endl;}

};

class Drive : public Base {

Drive(){}

~Drive(){cout<<"Drive::~Drive()"<<endl;}

virtual void Work(){cout<<"Drive::Work"<<endl;}

};

Base *pBase = new Drive();

pBase->Work();

delete pBase

輸出：

Drive::Work

Base::~Base()

對象沒有被完全delete。

如果在~Base()之前加上virtual ，輸出

Drive::Work

Drive::~Drive()

Base::~Base()