Compilare: user.cpp: In function ‘void eB()’: user.cpp:18:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(a.s[s.length()]=='2' && s.length()+1<=a.l){ ~~~~~~~~~~~~^~~~~ user.cpp:22:74: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] } else if(a.s[s.length()]=='1' && a.s[s.length()+2]=='3' && s.length()+3<=a.l){ ~~~~~~~~~~~~^~~~~ user.cpp: In function ‘void eC()’: user.cpp:35:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(a.s[s.length()]=='2' && s.length()<=a.l){ ~~~~~~~~~~^~~~~ user.cpp:39:72: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if(a.s[s.length()]=='1' && a.s[s.length()+1]=='2' && s.length()+2<=a.l){ ~~~~~~~~~~~~^~~~~ user.cpp:45:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if(a.s[s.length()]=='3' && s.length()+2<=a.l){ ~~~~~~~~~~~~^~~~~ user.cpp: In function ‘bool egal(std::__cxx11::string, std::__cxx11::string)’: user.cpp:57:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<a.size();i++){ ~^~~~~~~~~