How to define a derived class ?

A singly inherited derived class id defined by writing :

• The keyword class.
• The name of the derived class .
• A single colon (:).
• The type of derivation ( private , protected, or public ).
• The name of the base, or parent class.
• The remainder of the class definition.

e.g.

                class A

                 {

                  public :

                                                int public_A;

                                                void public_function_A();                           

  private :

                                                int pri_A;

                                                void private_function_A();

  protected :

                                                int protected_A;

                                                void protected_function_A();

  };

class B : private  A

 {

                  public :

                                                int public_B;

                                                void public_function_B();                            

       private :

                                                int pri_B;

                                                void private_function_B();

};

class C : public  A

 {

  public :

                                                int public_C;

                                                void public_function_C();                            

        private :

                                                int pri_C;

                                                void private_function_C();

 };

class D : protected A

 {

                  public :

                                                int public_D;

                                                void public_function_D();                                

                  private :

                                                int pri_D;

                                                void private_function_D();

                 };

A derived class always have all of the member members from its base class. You cannot "subtract" anything from a base class. Though, accessing the inherited variables is a dissimilar matter. It is also important to understand the privileges that the derived class has insofar as access to members of its base class are concerned. In other words, just because you happen to derive a class does not mean that you are automatically granted complete and unlimited access privileges to the members of the base class. to understand this you must look at the dissimilar types of derivation and the effect of each one.