1 #include <stdio.h> 2 3 #pragma weak undef_data 4 5 extern int undef_data; 6 int *ptr_to_data = &undef_data; 7 8 int main(void)9 main (void) 10 { 11 if (ptr_to_data == NULL) 12 printf ("PASSED\n"); 13 14 return 0; 15 } 16