Compilare: user.cpp: In member function ‘void Trie::add(std::string)’: user.cpp:92:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.length(); i++) { ^ user.cpp:99:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == s.length() - 1) ^ user.cpp: In member function ‘int Trie::get(std::string)’: user.cpp:106:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.length(); i++) { ^ user.cpp:110:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == s.length() - 1) ^ user.cpp: In member function ‘int Trie::lpm(std::string)’: user.cpp:122:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; i < s.length(); i++) { ^ user.cpp: In member function ‘TrieNode* Trie::del_rec(std::string, TrieNode*, int)’: user.cpp:136:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == s.size() && node->count > 0) { ^