// RunningAvg.cpp

#include <list>
#include <iostream>

template <typename T>
class RunAvg
{
public:
  RunAvg(unsigned int N);
  void add(const T& t);
  T avg() const;
private:
  RunAvg(const RunAvg&);
  RunAvg& operator=(const RunAvg&);
  unsigned int _N;
  std::list<T> store;
};

template <typename T>
RunAvg<T>::RunAvg(unsigned int N) : _N(N) {}

template <typename T>
void RunAvg<T>::add(const T& t)
{
  store.push_back(t);
  if(store.size() > _N)
    store.pop_front();
}

template <typename T>
T RunAvg<T>::avg() const
{
  if(store.size() == 0)
    return 0;
  T sum = 0;
  std::list<T>::const_iterator iter;
  for(iter=store.begin(); iter!=store.end(); ++iter)
    sum += *iter;
  return sum/store.size();
}

int main()
{
  std::cout << "\n  Testing Running Average "
            << "\n =========================\n";

  RunAvg<double> ra(4);
  for(int i=0; i<10; i++)
  {
    ra.add(i);
    std::cout << "\n  " << ra.avg();
  }
  std::cout << "\n\n";
}