Compilare: main.cpp: In function 'void insertus(trie*, char*)': main.cpp:34:15: warning: NULL used in arithmetic [-Wpointer-arith] 34 | if (*s != NULL) | ^~~~ main.cpp: In function 'void deletus(trie*, char*)': main.cpp:48:15: warning: NULL used in arithmetic [-Wpointer-arith] 48 | if (*s != NULL) | ^~~~ main.cpp: In function 'int prefix(trie*, char*)': main.cpp:70:23: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare] 70 | for (int i = 0; i < strlen(s); ++i) | ~~^~~~~~~~~~~