Hierarchical Inheritance

• The form of inheritance in which more than one classes are derived from single base class is known as hierarchical inheritance. We can implement the hierarchical inheritance by defining at least three classes in which one base class and the remaining two classes are derived classes. These two derived classes should be derived the same base class.
• It is the inheritance hierarchy wherein multiple subclasses are inherited from one base class. 

Diagram:

Example :

 

Syntax:
    class base_class_name
    {
        private:
        …………….
        public:
        …………….
    };
    class derived_class_name1 : public base_class_name
    {
        private:
        ……………
        public:
        ……………
    };
    class derived_class_name2 : public base_class_name
    {
        private:
        …………..
        public:
        …………..
    };

Sample Program:

    #include <iostream.h>
    class Side
      {
            protected:
              int l;
            public:
              void set_values (int x)
                {
             l=x;
        }
      };
    class Square: public Side
      {
            public:
              int sq()
              {  
            return (l *l);
        }
      };

    class Cube:public Side
      {
           public:
             int cub()
              {
            return (l *l*l);
        }
      };
    int main ()
      {
           Square s;
            s.set_values (10);
           cout << "The square value is::" << s.sq() << endl;
           Cube c;
            c.set_values (20);
           cout << "The cube value is::" << c.cub() << endl;
            return 0;
      }

Advantages:

• code re-usability.
• Saves time in program development. 

Disadvantages:

• Though object-oriented programming is frequently program as an answer for complicated project,inappropriate use of inheritance makes a program more complicated.
• Invoking member function using object create more compiler overheads.
• In class hierarchy various data elements remains unused,the memory allocated to them is not utilized.