Compilare: user.cpp: In function ‘int main()’: user.cpp:23:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i!=string::npos) ^ user.cpp:30:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<b.size()&&i<1000;i++) out<<b.at(i)<<" "; ^ user.cpp:13:7: warning: variable ‘z’ set but not used [-Wunused-but-set-variable] char z; ^