Compilare: user.cpp:3:19: warning: extra tokens at end of #include directive [enabled by default] #include <fstream>; ^ user.cpp: In function ‘std::ostream& operator<<(std::ostream&, const std::vector<int>&)’: user.cpp:12:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < x.size(); i++) ^ user.cpp:13:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] g << x[i] << " \n"[i == (x.size() - 1)]; ^