Compilare: user.c: In function ‘read’: user.c:13:13: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(FIN, "r", stdin); ^ user.c:15:11: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &num); ^ user.c:21:36: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] for(i = 0; i < num; ++i) scanf("%d ", &p[i]); ^ user.c: In function ‘write’: user.c:67:13: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(FOUT, "w", stdout); ^ user.c: In function ‘main’: user.c:79:9: warning: ‘arr’ is used uninitialized in this function [-Wuninitialized] arr = read(arr, &n); //passing by reference ^