Compilare: user.cpp: In function ‘int main()’: user.cpp:42:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < S.length(); ++i) { ^ user.cpp:43:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (len[i] == s.length()-1) ^ user.cpp:47:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < S.length(); ++i) { ^ user.cpp:48:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (len[i] == s.length()-1) ^