number of elements in c 2b 2b array

1#include <iostream>
2using std::cout;
3
4int a[] = { 1, 2, 3, 4, 5 };
5int counta()
6  {
7  return sizeof( a ) / sizeof( a[ 0 ] );  // works, since a[] is an array
8  }
9
10int countb( int b[] )
11  {
12  return sizeof( b ) / sizeof( b[ 0 ] );  // fails, since b[] is a pointer
13  }