C++ Program on Data Abstraction

   #include <iostream>
   using namespace std;
   class Adder
   {
     public:
       // constructor
       Adder(int i = 0)
       {
         total = i;
       }
       // interface to outside world
       void addNum(int number)
       {
         total += number;
       }
       // interface to outside world
       int getTotal()
       {
         return total;
       };
       private:
         // hidden data from outside world
         int total;
   };
   int main( )
   {
     Adder a;
     a.addNum(10);
     a.addNum(20);
     a.addNum(30);
     cout << "Total " << a.getTotal() <<endl;
     return 0;
   }