1  int n = 50;
       2  
       3  void
       4  foo (int a[])
       5  {
       6    int i;
       7    for (i = n - 20; i < 50; i++)
       8      a[i] = i;
       9  }
      10  
      11  int
      12  array_sum (int a[])
      13  {
      14    int i;
      15    int res = 0;
      16    for(i = n - 20; i < n; i *= 2)
      17      res += a[i];
      18    return res;
      19  }
      20  
      21  extern void abort ();
      22  
      23  int
      24  main (void)
      25  {
      26    int a[50];
      27    foo (a);
      28    int res = array_sum (a);
      29    if (res != 30)
      30      abort ();
      31    return 0;
      32  }