Compilare: user.cpp: In member function ‘bool Trie::del(Trie::Node*, std::__cxx11::string, int)’: user.cpp:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(index == word.size()) ~~~~~~^~~~~~~~~~~~~~ user.cpp:31:34: warning: array subscript has type ‘char’ [-Wchar-subscripts] Node* node = curr->sons[c]; ^ user.cpp:35:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] curr->sons[c] = nullptr; ^ user.cpp: In member function ‘void Trie::add(std::__cxx11::string)’: user.cpp:46:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); i++) ~~^~~~~~~~~~~~~ user.cpp: In member function ‘int Trie::cnt(std::__cxx11::string)’: user.cpp:66:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); i++) ~~^~~~~~~~~~~~~ user.cpp: In member function ‘int Trie::prefix(std::__cxx11::string)’: user.cpp:79:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); i++) ~~^~~~~~~~~~~~~