C++: Access control in privately derived class

Access control in privately derived class

From a privately derived class, public and protected members of the base class become private members of the derived class. Hence it is not possible to access the derived members using the object of the derived class.The Derived members are invoked by calling it from the publicly defined members

Illustration 16.10 the privately inherited derived class

#include<iostream>

#include<string>

using namespace std;

class Employee

{

private:

      char name[50];

      int code;

public:

      void getinfo();

      void dispinfo();

};

class staff: private Employee

{

private:

      int ex;

public:

      void getdata();

      void display();

};

void Employee::getinfo()

{

      cout<<"Name:";

      gets(name);

      cout<<"Code:";

      cin>>code;

}

void Employee::dispinfo()

{

      cout<<"Name:"<<name<<endl;

      cout<<"Code:"<<code<<endl;

}

void staff::getdata()

{

      getinfo();         //invoked inside

      cout<<"Experience:";

      cin>>ex;

}

void staff::display()

{

dispinfo();                 //member function called inside another member function

cout<<"Experience:"<<ex<<" Years"<<endl;

}

int main()

{

staff s;

cout<<"Enter data"<<endl;

      s.getdata();

cout<<endl<<endl<<"\tDisplay Data"<<endl;

      s.display();

return 0;

}

Output:

Enter data

Name: BALAMURUGAN

Code: 1201

Experience: 30

Display Data

Name: BALAMURUGAN

Code: 1201

Experience: 30 Years

If you look at the output of publicly derived class and privately derived class are same the way of defining is different. This is because the private members of the derived class cannot be accessed by its object. In the above program since staff is privately derived getinfo() and dispinfo() become private to class “staff”. To access both the member function they are invoked inside the publ;ic member functions getdata() and display() respectively.

Member functions can access the private members