Compilare: user.c: In function ‘main’: user.c:15:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("euclid2.in", "r", stdin); ^ user.c:16:10: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("euclid2.out", "w", stdout); ^ user.c:18:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.c:21:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &g_a, &g_b); ^ user.c: In function ‘gcd’: user.c:10:2: warning: ‘c’ may be used uninitialized in this function [-Wmaybe-uninitialized] return (b); ^