Re: 2 dimensional array within function

"Giovanni Dicanio" <>
Wed, 6 Feb 2008 16:38:05 +0100
"David Wilkinson" <> ha scritto nel messaggio

Both these problems would not occur if you used std::vector.

I agree with David Wi.

std::vector, and STL containers in general, seem to offer better
"composibility" than MFC containers.

Moreover, if the purpose is to store a 2D matrix like MxN, then a viable
solution could be also to use a single std::vector (or even valarray), sized
M*N (rowCount * coumnCount), and provide a method to address each element,
converting from (row, column) pair index to a single index to access the
array, using a formula like this:

  index = col + row*columnCount


  template <typename T>
  class Matrix
        explicit Matrix( int columnCount, int rowCount )
          : m_data( columnCount * rowCount ), // set matrix size
            m_columnCount( columnCount ),
            m_rowCount( rowCount )

      const T & at( int row, int column ) const
         ASSERT( row >= 0 && row < m_rowCount );
         ASSERT( column >= 0 && column < m_columnCount );
         // Access specific element in 1D array
         // (convert from 2D (row, column) to 1D array index)
         return column + row * m_columnCount );


     std::vector< T > m_data;
     int m_columnCount;
     int m_rowCount;


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