title: how to refer to a column of a 2D array (matrix) in C++
body: <p>I have declared a 2D array in the following way (please note that I'm very beginner!)</p>
  
  <pre><code>double **A=new double*[10];
  
  for(int i=0;i&lt;10;i++)
      A[i]=new double[5];
  </code></pre>
  
  <p>So I guess this already defines a matrix of size 10 by 5.</p>
  
  <p>I know that to refer to its row I can use </p>
  
  <pre><code>A[i]
  </code></pre>
  
  <p>But the question is, how to refer to a column of A? something like A[][i]? </p>