class Base{
public:
int Base_public;
protected:
int Base_protected;
private:
int Base_private;
};
class Derived:public Base{
public:
int Derived_public;
protected:
int Derived_protected;
private:
int Derived_private;
public:
void Check();
void Check(Base& vBase,Derived& vDerived);
};
void Derived::Check()
{
//this 是Derived类型的，在this所属类作用域(Derived作用域)里
//，Derived本身定义的变量，无论什么访问标号都可以
Derived_private =5; //ok
Derived_protected=5; //ok
Derived_public = 5; //ok
//Derived继承Base来的变量，可以访问Base中public和protected标号的成员变量
Base_public =5;//ok
Base_protected =5;//ok
//Base_private =5;//error
//给每个变量前加上this指针，更方便理解
//类类型变量在所属类作用域里，变量中由所属类自身定义的成员变量可以任意访问
//所属类继承来的变量，只可以访问public和protected成员变量
//类类型变量在其他作用域里，只能访问public成员变量
}
//
void Derived::Check(Base &vBase,Derived &vDerivde)
{
//vBase是Base类型，在Derived类作用域里（非本身作用域）,只能访问public标示的成员变量
//vBase.Base_private =5;//error
//vBase.Base_protected =5;//error
vBase.Base_public =5;//ok
//vDerived是Derived类型，在Derived作用域里（本身作用域）,所属类定义的变量，可任意访问
vDerivde.Derived_public =5;//ok
vDerivde.Derived_protected =5;//ok
vDerivde.Derived_private =5;//ok
//所属类继承来的变量，只能访问public,protected
//vDerivde.Base_private =5;//error
vDerivde.Base_protected =5;//ok
vDerivde.Base_public =5;//ok
//private任何时候只能在本身作用域使用
}
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