class B: public a 派生类 public void fnO int as IvA a- priv ∥错误:不可访问 a= protA; 有效 a pubA /效 }; 人民邮电出版社 POSTS tEl OM PRE 动此映class B : public A //派生类 { public: void fn() { int a; a = privA; //错误：不可访问 a = protA; //有效 a = pubA; //有效 } };