Compilare: user.cpp: In function ‘int main()’: user.cpp:8:12: warning: unused variable ‘n’ [-Wunused-variable] int t, n, a, b, r, op; ^ user.cpp:6:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numere.in", "r", stdin); ^ user.cpp:7:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numere.out", "w", stdout); ^ user.cpp:9:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (scanf("%d", &t); t > 0; --t) ^ user.cpp:11:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^