Compilare: user.cpp: In function ‘int main()’: user.cpp:65:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; s[j] != '.' && j < s.size(); j++) ^ user.cpp:71:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j < s.size()) ^ user.cpp:79:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; s[j] != '.' && j < s.size(); j++) ^ user.cpp:85:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j < s.size()) ^