Compilare: user.cpp: In function ‘int verifica(std::string)’: user.cpp:13:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<s1.length();i++) ^ user.cpp: In function ‘char BiToCh(std::string)’: user.cpp:48:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<b.length();i++){ ^ user.cpp: In function ‘void rs(std::string)’: user.cpp:58:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<s.length();i++) ^