1 extern void abort(void); foo(int * p)2 void foo(int *p) 3 { 4 int x; 5 int y; 6 x = *p; 7 *p = 0; 8 y = *p; 9 if (x != y) 10 return; 11 abort (); 12 } 13 main()14 int main() 15 { 16 int a = 1; 17 foo(&a); 18 return 0; 19 } 20