how to find 2d array size in c++

Suppose you were only allowed to use an array, then you could find the size of a 2-D array in the following way.

  int ary[][5] = { {1, 2, 3, 4, 5},
                   {6, 7, 8, 9, 0}
                 };

  int rows = sizeof ary / sizeof ary[0]; // 2 rows  

  int cols = sizeof ary[0] / sizeof(int); // 5 cols