Compilare: user.cpp: In function ‘void factorial()’: user.cpp:13:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=s.size()+1;i++) ^ user.cpp: In function ‘int main()’: user.cpp:41:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int it=0;it<= s.size()-1;it++) ^