///////////////////////////////////////////////////////////////////
// circBuf.cpp - Solution of MT#4-Q2                             //
//                                                               //
// This is a demo showing how to make the required declarations  //
// It provides no useful functionality.                          //
///////////////////////////////////////////////////////////////////

template <typename T>
class circBuf
{
  public:
    circBuf(int size);
    circBuf(const circBuf<T>& cb);
    ~circBuf();
    circBuf& operator=(const circBuf& cb);
    void add(const T& t);
    T& operator[](int n);
    T operator[](int n) const;
  private:
    int _size;  // capacity of buffer
    int _last;  // index of last element entered
    T* pBuf;
};

//----< return n from the last element >-----------------------------

template<typename T>
circBuf<T>::circBuf(int size) : _size(size), pBuf(new T[size]) { }

//----< return n from the last element >-----------------------------

template<typename T>
circBuf<T>::~circBuf()
{
  delete [] pBuf;
}

//----< return n from the last element >-----------------------------

template<typename T>
T& circBuf<T>::operator[](int n)
{
  if(n > size + _last)
    throw "domain error in index operator";
  return (_last - n + size)%_size;
}

int main()
{
  circBuf<double> cb(10);
  return 0;
}