C++ General: How to declare and use two-dimensional arrays?

[Andreas Masur]

Q: How can I define a dynamic two-dimensional array?

A: The following class shows one way of encapsulating a two-dimensional array:

template <class T>
class dynamic_2d_array
{
public:
  dynamic_2d_array(int row, int col) : m_row(row),
                                       m_col(col),
                                       m_data((row != 0 && col != 0) ? new T[row * col] : NULL){}

  dynamic_2d_array(const dynamic_2d_array& src) : m_row(src.m_row),
                                                  m_col(src.m_col),
                                                  m_data((src.m_row != 0 && src.m_col != 0) ? new T[src.m_row * src.m_col] : NULL)
  {
    for(int r = 0;r < m_row; ++r)
      for(int c = 0; c < m_col; ++c)
        (*this)[r][c] = src[r][c];
  }

  ~dynamic_2d_array()
  {
    if(m_data)
      delete []m_data;
  }
  
  inline T* operator[](int i) { return (m_data + (m_col * i)); }

  inline T const*const operator[](int i) const {return (m_data + (m_col * i)); }


private:
  dynamic_2d_array& operator=(const dynamic_2d_array&);
  const int m_row;
  const int m_col;
  T* m_data; 
};

A different approach using the STL 'vector' class is shown in the following FAQ...


FAQ contributed by: [Axter]