Compilare: user.c: In function ‘gen_primes’: user.c:85:15: warning: unused variable ‘i’ [-Wunused-variable] int a, j, i; ^ user.c: In function ‘read_eval’: user.c:28:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.c:32:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s%d%d", op, &a, &b); ^ user.c:45:22: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &c, &d); ^ user.c: In function ‘main’: user.c:127:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("perspic.in", "rt", stdin); ^ user.c:128:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("perspic.out", "wt", stdout); ^