析构函数为虚函数的必要性

在实现多态时，当用基类操作派生类，在析构时防止只析构基类而不析构派生类的状况发生。
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
输出：Drive::WorkBase::~Base()对象没有被完全delete。
如果在~Base()之前加上virtual ，输出Drive::WorkDrive::~Drive()Base::~Base()