#include <iostream>
#include <string>
using namespace std;
class StudentA //（1）修改studentA類中各資料成員和成員函式的訪問限定符為public時沒有出現錯誤，修改為private時顯示錯誤為error2248即私有成員不能再派生類內使用。
{
public:
    StudentA(int n,string nam,char s);
    	void showA();
    ~StudentA( ) { }
protected:

    int num;
    string name;
    char sex ;
};


class StudentB: public StudentA //（2）將此處的繼承方式改為protected時，出現錯誤。即保護成員只能在類內使用不能再類外使用。
{
public:
    StudentB(int n,string nam,char s,int a,string ad);
    void showB( );
    ~StudentB( ) { }
private:
    int age;
    string addr;
};


StudentA::StudentA(int n,string nam,char s)
{
    num=n;
    name=nam;
    sex=s;
}
void StudentA::showA()
{
    cout<<"num: "<<num<<endl;
    cout<<"name: "<<name<<endl;
    cout<<"sex: "<<sex<<endl<<endl;
}


StudentB::StudentB(int n,string nam,char s,int a,string ad):StudentA(n,nam,s)
{
    age=a;
    addr=ad;
}
void StudentB::showB( )
{
    cout<<"num: "<<num<<endl;
    cout<<"name: "<<name<<endl;
    cout<<"sex: "<<sex<<endl;
    cout<<"age: "<<age<<endl;
    cout<<"address: "<<addr<<endl<<endl;
}


int main( )  
{
    StudentB stud1(10010,"Wang-li",'f',19,"115 Beijing Road,Shanghai");
    StudentB stud2(10011,"Zhang-fun",'m',21,"213 Shanghai Road,Beijing");
    StudentA stud3(20010,"He-xin",'m');
    stud1.showB( );
    stud2.showA( );
    stud3.showA( );
    return 0;
}
執行結果：