Compilare: user.cpp: In function ‘void prefix(std::string)’: user.cpp:26:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < s.size()) ^ user.cpp: In function ‘int main()’: user.cpp:59:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < s.size()) ^ user.cpp:66:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (q == s2.size()) ^ user.cpp:76:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) ^