Compilare: user.cpp: In function ‘int Modulo(std::string)’: user.cpp:32:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < S.length(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:50:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cifra.in","r",stdin); ^ user.cpp:51:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cifra.out","w",stdout); ^