Compilare: user.cpp: In function ‘long long int ConvertToLL(std::string)’: user.cpp:17:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < Str.length(); ++ i) ^ user.cpp: In function ‘std::string ConvertToString(long long int)’: user.cpp:36:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < D.size() - 14; ++ i) ^ user.cpp:42:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = D.size() - 14; i < D.size() - 14 + 10; ++ i) ^