/* 
  Function Object
*/
#include <iostream>
#include <cstdlib>
using namespace std;

/* function will not work - can not hold value between calls.
void f(int i){
   int hold;
   hold += i;
}
*/

// use this object fadd to implement a function like object
// that can hold values between calls.
// fadd, since it overloads the () operator, is called a 
// function object.
class fadd{
	int hold;
public:
	fadd():hold(0){}
	int operator()(int a){hold += a; return  hold;}
};

int main(int nargs, char **args){
   int x = 3;
   fadd f; // declare an instance of fadd - create an object.
   cout << f(x) << endl;
   cout << f(4) << endl;

   return EXIT_SUCCESS;
}