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: 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: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: 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 ) ^ user.cpp: In member function ‘int nrx_state_machine::count_occurrences(nrx_state_machine::trie_node*, char*)’: user.cpp:77:26: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) ^ user.cpp: In member function ‘int nrx_state_machine::longest_prefix(nrx_state_machine::trie_node*, char*, int)’: user.cpp:87:26: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) ^ user.cpp: In member function ‘void nrx_state_machine::reset_machine(nrx_state_machine::trie_node*)’: user.cpp:97:37: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] node -> cnt_occurrences = NULL; ^ user.cpp: In member function ‘void nrx_state_machine::build_occurrences(nrx_state_machine::trie_node*, char*)’: user.cpp:141:42: warning: NULL used in arithmetic [-Wpointer-arith] for( *word = *word; *word != NULL; word ++ ) { ^ user.cpp: In member function ‘void nrx_state_machine::build_partial_sum(nrx_state_machine::trie_node*)’: user.cpp:156:57: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]