title: Calculate number of rows in constant 2D c-array
body: <p>alculating number of elements in array is easy:</p>
  
  <pre><code>int myarr[] ={1,2,3};
  int myarrsize = sizeof(myarr)/sizeof(myarr[0]);
  </code></pre>
  
  <p>but, how can I calculate number of rows in 2D array?</p>
  
  <pre><code>int my2Darr[][3]={{1,2,3},{4,5,6}};
  int my3DarrRows = ???
  </code></pre>
  
  <p>Is it possible?</p>