Multilevel Inheritance

When a class is derived from another derived class is called as multilevel inheritance. 

It is implemented by defining at least three classes. In multilevel inheritance, there is one base class and the remaining two are derived class. 

Diagrammatic representation:

Syntax
    class A {/* ... */ };
    class B: public A { /* ... */ };
    class C :public B{ /* ... */ };

Sample program:

     class A
    {
        public:  void display ()
        {
            cout<<"Base class content.";
        }
     };
    class B : public A
    {
        ….....
    };
  
    class C: public B
    {
        ….......
     }; 

    int main()
    {
        C c;
        c.display();
        return 0;
    } 

Output:

base class content

Advantages:

• Allows the code to be reused as many times as needed. The base class once defined and once it is compiled, it need not be reworked.
• Saves time and effort as the main code need not be written again.

Disadvantages

• In Inheritance base class and child classes are tightly coupled. Hence If you change the code of parent class, it will get affects to the all the child classes.
• In class hierarchy many data members remain unused and the memory allocated to them is not utilized. Hence affect performance of your program if you have not implemented inheritance correctly.