Compilare: user.cpp: In constructor ‘nrx_state_machine::trie_node::trie_node()’: user.cpp:18:30: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] cnt_children = NULL; cnt_words = NULL; ^ user.cpp:18:48: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] cnt_children = NULL; cnt_words = NULL; ^ user.cpp:19:51: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] back_node = NULL; cnt_occurrences = NULL; ^ user.cpp: In member function ‘void nrx_state_machine::insert_word(nrx_state_machine::trie_node*, char*)’: user.cpp:29:26: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) { ^ user.cpp:34:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] if( node -> child[ *word ] == NULL ) { ^ user.cpp:35:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] node -> child[ *word ] = new trie_node; ^ user.cpp:39:47: warning: array subscript has type ‘char’ [-Wchar-subscripts] insert_word( node -> child[ *word ], word + 1 ); ^ user.cpp: In member function ‘bool nrx_state_machine::erase_word(nrx_state_machine::trie_node*, char*)’: user.cpp:44:26: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) node -> cnt_words --; else ^ user.cpp:45:50: warning: array subscript has type ‘char’ [-Wchar-subscripts] if( erase_word( node -> child[ *word ], word + 1 ) ) ^ user.cpp:48:57: warning: NULL used in arithmetic [-Wpointer-arith] if( node != root && node -> cnt_children == NULL && node -> cnt_words == NULL ) { ^ user.cpp:48:86: warning: NULL used in arithmetic [-Wpointer-arith] if( node != root && node -> cnt_children == NULL && node -> cnt_words == NULL ) { ^ user.cpp: In member function ‘bool nrx_state_machine::find_word(nrx_state_machine::trie_node*, char*)’: user.cpp:57:26: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) ^ user.cpp:60:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] if( node -> child[ *word ] != NULL ) ^ user.cpp:61:56: warning: array subscript has type ‘char’ [-Wchar-subscripts] return find_word( node -> child[ *word ], word + 1 ); ^ user.cpp: In member function ‘int nrx_state_machine::count_word(nrx_state_machine::trie_node*, char*)’: user.cpp:67:26: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) ^