第十二周 任务一

#include<iostream>#include<string>using namespace std;class Student //（1）修改student类中各数据成员和成员函数的访问限定符，并观察发生的现象{public: Student(int n,string nam,char s) ;void show();~Student( ){ } protected: int num;string name;char sex ; };class Student1: public Student //（2）修改此处的继承方式，并观察发生的现象{public:     Student1(int n,string nam,char s,int a,string ad);void show1( );~Student1( ){ } private: int age; string addr; };Student::Student(int n,string nam,char s) {num=n;name=nam;sex=s; }void Student::show(){cout<<"num: "<<num<<endl;cout<<"name: "<<name<<endl;cout<<"sex: "<<sex<<endl<<endl;}Student1::Student1(int n,string nam,char s,int a,string ad):Student(n,nam,s) {age=a; addr=ad;}void Student1::show1( ){cout<<"num: "<<num<<endl;cout<<"name: "<<name<<endl;cout<<"sex: "<<sex<<endl;cout<<"age: "<<age<<endl;cout<<"address: "<<addr<<endl<<endl;}int main( ){Student1 stud1(10010,"Wang-li",'f',19,"115 Beijing Road,Shanghai");Student1 stud2(10011,"Zhang-fun",'m',21,"213 Shanghai Road,Beijing");Student stud3(20010,"He-xin",'m');stud1.show1( ); stud2.show( ); stud3.show( ); system("pause");return 0;}

 

1.把class Student1: public Student改为private Student，提示错误：'show' : cannot access public member declared in class 'Student'！

则Student类里的成员函数void show();变成私有函数，禁止Student类外的对象访问。

 

2.把Student中的 publicStudent 改为protected Student，出现3个错误，1.'Student::Student' : cannot access protected member declared in class 'Student'！ 2.'Student::~Student' : cannot access protected member declared in class 'Student'！  3.'show' : cannot access protected member declared in class 'Student'！

 

3.把class Student1: public Student改为protectedStudent，提示错误：'show' : cannot access public member declared in class 'Student'！

说明Student类里的成员函数void show();变成了受保护类型的，不允许Student类的对象直接访问。

 

1.派生类中访问属性为public的成员在派生类内部和外部都可以访问。

2.派生类中访问属性为private的成员在派生类内部可以访问，在派生类外部不可以访问。

3.派生类中访问属性为protected的成员在派生类内部可以访问，在派生类外部不可以访问。

 

num: 10010
name: Wang-li
sex: f
age: 19
address: 115 Beijing Road,Shanghai

num: 10011
name: Zhang-fun
sex: m

num: 20010
name: He-xin
sex: m

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