Compilare: main.cpp: In function 'Node* add(Node*, const char*)': main.cpp:19:14: warning: NULL used in arithmetic [-Wpointer-arith] 19 | if(w[0]==NULL) | ^~~~ main.cpp: In function 'Node* eradicate(Node*, const char*)': main.cpp:29:14: warning: NULL used in arithmetic [-Wpointer-arith] 29 | if(w[0]==NULL) | ^~~~ main.cpp: In function 'int query_no_apps(Node*, const char*)': main.cpp:45:14: warning: NULL used in arithmetic [-Wpointer-arith] 45 | if(w[0]==NULL) | ^~~~ main.cpp: In function 'int query_prefix(Node*, const char*)': main.cpp:52:25: warning: NULL used in arithmetic [-Wpointer-arith] 52 | if(p==NULL || w[0]==NULL) | ^~~~