Compilare: user.cpp: In function ‘std::string trans(const string&)’: user.cpp:62:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sir.size(); i++) ^ user.cpp:66:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = i; j < sir.size(); j++) ^ user.cpp: In function ‘void get_molecules(std::string)’: user.cpp:89:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sir.size(); i++) ^