Compilare: main.cpp: In function 'void insert_trie(trie*, char*)': main.cpp:28:14: warning: NULL used in arithmetic [-Wpointer-arith] 28 | if(*s == NULL) | ^~~~ main.cpp: In function 'bool delete_trie(trie*, char*)': main.cpp:44:14: warning: NULL used in arithmetic [-Wpointer-arith] 44 | if(*s == NULL) | ^~~~ main.cpp: In function 'int query_trie(trie*, char*)': main.cpp:62:14: warning: NULL used in arithmetic [-Wpointer-arith] 62 | if(*s == NULL) | ^~~~ main.cpp: In function 'int prefix_trie(trie*, char*, int)': main.cpp:72:14: warning: NULL used in arithmetic [-Wpointer-arith] 72 | if(*s == NULL) | ^~~~