Nested class is a class defined inside a class, that can be used within the scope of the class in which it is defined. In C++ nested classes are not given importance because of the strong and flexible usage of inheritance. Its objects are accessed using "Nest::Display".

   #include <iostream.h>
   class Nest
    {
      public:
       class Display
        { 
         private:
          int s;
         public:
          void sum( int a, int b)
            {  s =a+b; }
          void show( )
            { cout << "\nSum of a and b is:: " << s;}
        };
    };
   void main()
    {
       Nest::Display x;
       x.sum(12, 10);
       x.show();
    }

    Sum of a and b is::22

In the above example, the nested class "Display" is given as "public" member of the class "Nest".