Compilare: user.cpp: In function ‘int verifica(std::string)’: user.cpp:13:31: 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:51:30: 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:62:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < s.length(); i++) ^