Compilare: main.cpp: In function 'void add_word(n_trie*, char*)': main.cpp:30:18: warning: NULL used in arithmetic [-Wpointer-arith] if (*word == NULL) { ^~~~ main.cpp: In function 'int query_word(n_trie*, char*)': main.cpp:60:29: warning: array subscript has type 'char' [-Wchar-subscripts] if (node -> children[chr] == NULL) { ^ main.cpp:67:36: warning: array subscript has type 'char' [-Wchar-subscripts] query_word(node -> children[chr], word + 1); ^ main.cpp:69:1: warning: control reaches end of non-void function [-Wreturn-type] } ^