Compilare: user.cpp: In function ‘int f(const string&)’: user.cpp:11:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < cuv.size(); ++i) { ^ user.cpp:24:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v.size(); ++i) { ^