Declaring and allocating a 2d array in C++

Question

I am a Fortran user and do not know C++ well enough. I need to make some additions into an existing C++ code. I need to create a 2d matrix (say A) of type double whose size (say

Answer 1

I would recommend using std::vector and avoid all the headache of manually allocating and deallocating memory.

Here's an example program:

#include 
#include 

typedef std::vector Row;
typedef std::vector Matrix;

void testMatrix(int M, int N)
{
   // Create a row with all elements set to 0.0
   Row row(N, 0.0);

   // Create a matrix with all elements set to 0.0
   Matrix matrix(M, row);

   // Test accessing the matrix.
   for ( int i = 0; i < M; ++i )
   {
      for ( int j = 0; j < N; ++j )
      {
         matrix[i][j] = i+j;
         std::cout << matrix[i][j] << " ";
      }
      std::cout << std::endl;
   }
}

int main()
{
   testMatrix(10, 20);
}