Compilare: user.cpp: In member function ‘void Trie::add_word(std::__cxx11::string&)’: user.cpp:58:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < word.size();i++){ ~~^~~~~~~~~~~~~ user.cpp:64:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i == word.size() - 1){ ~~^~~~~~~~~~~~~~~~~~ user.cpp: In member function ‘void Trie::remove_word_recursive(TrieNode*&, std::__cxx11::string&, int)’: user.cpp:76:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(position == word.size()){ ~~~~~~~~~^~~~~~~~~~~~~~ user.cpp:82:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(position == word.size() - 1){ ~~~~~~~~~^~~~~~~~~~~~~~~~~~ user.cpp: In member function ‘int Trie::count_word(std::__cxx11::string&)’: user.cpp:93:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < word.size();i++){ ~~^~~~~~~~~~~~~ user.cpp:98:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i == word.size() - 1){ ~~^~~~~~~~~~~~~~~~~~ user.cpp: In member function ‘int Trie::longest_prefix(std::__cxx11::string&)’: user.cpp:108:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < word.size();i++){ ~~^~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:128:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.in", "r", stdin); ^ user.cpp:129:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.out", "w", stdout); ^ user.cpp:132:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s); ^