条款51：编写new和delete时需固守常规

      很多人没有意识到operator new成员函数会被derived classes继承,那就会出现,有可能base class的operator new被调用用以分配derived class对象。因此 derived class的 operator new的代码建议：

struct Base{ static void* operator new(std::size_t size) throw( std::bad_alloc ); ... }; struct Derived:public Base{...}; Derived* p = new Derived;//call Base::operator new. void* Base::operator new(std::size_t size) throw(std::bad_alloc) { if( size != sizeof(Base) ){ return ::operator new( size ); //call standard operator new version. } ... }

其余略