Перегрузка оператора "+" в классе

template <typename T>
class Array2D
{
public:
  // constructor
  Array2D(unsigned wd,unsigned ht)
    : nWd(wd), nHt(ht), pAr(0)
  {
    if(wd > 0 && ht > 0)
      pAr = new T[wd * ht];
  }
 
  // destructor
  ~Array2D()
  {
    delete[] pAr;
  }
 
 
// indexing (parenthesis operator)
  //  two of them (for const correctness)
 
  const T& operator () (unsigned x,unsigned y) const
  {  return pAr[ y*nWd + x ];   }
 
  T& operator () (unsigned x,unsigned y)
  {  return pAr[ y*nWd + x ];   }
 
// get dims
  unsigned GetRows()  const { return nWd; }
  unsigned GetColns() const { return nHt; }
 
 
// private data members
private:
  unsigned nWd;
  unsigned nHt;
  T*       pAr;
 
  // to prevent unwanted copying:
  Array2D(const Array2D<T>&);
  Array2D& operator = (const Array2D<T>&);
};

 template<typename R> Array2D<T> operator+(const Array2D<R> &A)const{
   Array2D<int> result(nWd,nHt) ;
   for(unsigned i = 0; i<nWd ; ++i){
    for(unsigned j = 0; j<nHt ; ++j){
      result(i,j) = A(i,j) + pAr[i*nWd + j] ;
                  }
                }
 return result;
}

template<class T>
T ** Array2DAlloc(unsigned a1, unsigned a2) {
    T ** ppA = new (T *)[a1];
    ppA[0] = new T[a1 * a2];
    for (unsigned i = 1; i < a1; ++i)
        ppA[i] = ppA[i - 1] + a2;
}
 
template<class T>
void Array2DFree(T ** ppA) {
    delete[] ppA[0];
    delete[] ppA;
}