Compilare: main.cpp: In function 'void gen_primes()': main.cpp:85:15: warning: unused variable 'i' [-Wunused-variable] int a, j, i; ^ main.cpp: In function 'void read_eval()': main.cpp:28:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:32:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s%d%d", op, &a, &b); ^ main.cpp:45:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &c, &d); ^ main.cpp: In function 'int main()': main.cpp:127:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("perspic.in", "rt", stdin); ^ main.cpp:128:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("perspic.out", "wt", stdout); ^