Compilare: user.cpp: In function ‘int main()’: user.cpp:19:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < s.size(); i++) ^ user.cpp:27:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[i] != ' ' && i < s.size()) ^ user.cpp:36:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[i] != ' ' && i < s.size()) ^