Compilare: user.cpp: In function ‘int main()’: user.cpp:16:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i<s.length()){ ^ user.cpp:17:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i<s.length() && s[i]!='-' && s[i]!='+' && s[i]!='='){ ^ user.cpp:22:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<el.length()-1; j++){ ^ user.cpp:30:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<el.length(); j++){ ^