Compilare: main.cpp: In function 'int main()': main.cpp:56:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int d = prime[0], k = 0; k < prime.size() && d * d <= nr; k++, d = prime[k]) { ~~^~~~~~~~~~~~~~ main.cpp: In function 'char nxt()': main.cpp:20:31: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, DIM, stdin); ^ main.cpp: In function 'int main()': main.cpp:49:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sprim.in", "r", stdin); ^ main.cpp:50:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sprim.out", "w", stdout); ^