Single Inheritance – Private Inheritance in C++

Let us understand what does private inheritance mean…

Consider a simple example to illustrate the single inheritance. The Program given below shows a base class B and a derived class D. The class B contains one private data member, one public data member and three public member functions. The class D contains one private data member and two public member functions.

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#include<iostream.h> class B    {       private:          int a;      //private; not inheritable       public:          int b;      //public; ready for inheritance          void get_ab();          int get_a();          void show_a();    }; class D : private B      //private derivation    {       private:          int c;       public:          void mul();          void display();    };

In private derivation, the public members of the base class becomes private members of the derived class. Therefore, the objects of the derived class D cannot have direct access to the public member functions of the base class B.

Hence, if we create an object of the derived class D,

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D x;

The statements such as:

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x.get_ab();   //get_ab() is private x.get_a();   //get_a() is private x.show_a();   //show_a() is private

will not work. However, these functions can be used inside mul() and display() like the normal functions as shown below:

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void mul()    {       get_ab();       c = b * get_a();    }   void display()    {       show_a();   //outputs value of a       cout << "b = " << b << endl;       cout << "c = " << c << endl;    }