Compilare: user.cpp: In function ‘int main()’: user.cpp:15:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) ^ user.cpp:19:62: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(isalpha(s[i]) || s[i]=='-' && i<s.size()) ^ user.cpp:19:50: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] while(isalpha(s[i]) || s[i]=='-' && i<s.size()) ^