C++PRIMER 4版 P483,该怎么处理

C++PRIMER 4版 P483

C/C++ code

class Base { public:     void basemem();   // public member protected:     int i;            // protected member     // ... }; struct Public_derived : public Base {     int use_base() { return i; } // ok: derived classes can access i     // ... }; struct Private_derived : private Base {     int use_base() { return i; } // ok: derived classes can access i };struct Derived_from Private : public Private_derived {     // error: Base::i is private in Private_derived     int use_base() { return i; } }; struct Derived_from_Public : public Public_derived {     // ok: Base::i remains protected in Public_derived     int use_base() { return i; } };

C/C++ code

struct Derived_from Private : public Private_derived {