Compilare: user.cpp: In function ‘void add(Trie*, std::string, int)’: user.cpp:29: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void remove(Trie*, std::string, int)’: user.cpp:47: warning: comparison between signed and unsigned integer expressions user.cpp:51: warning: array subscript has type ‘char’ user.cpp:52: warning: array subscript has type ‘char’ user.cpp:52: warning: array subscript has type ‘char’ user.cpp:54: warning: array subscript has type ‘char’ user.cpp:55: warning: array subscript has type ‘char’ user.cpp: In function ‘void print(Trie*, std::string, int)’: user.cpp:66: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void max_prefix(Trie*, std::string, int)’: user.cpp:86: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:122: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result