Compilare: user.cpp: In function ‘int longest()’: user.cpp:12:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++){ ^ user.cpp:18:53: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(pi[pos+len-1]>=best && pos+len-1<s.length()){ ^ user.cpp: In function ‘int main()’: user.cpp:30:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<s.length();i++){ ^