class Base { ... };
( a ) class Derived: public Derived { ... };
( b ) class Derived: private Base { ... };
( c ) class Derived: public Base;
class Base { ... };
//错误,派生类不能作为自己的基类
( a ) class Derived: public Derived { ... };
//正确
( b ) class Derived: private Base { ... };
//错误,声明不能有派生列表
( c ) class Derived: public Base;