Compilare: user.cpp: In function ‘void trieAdd(TRIE*, char*)’: user.cpp:27:34: warning: NULL used in arithmetic [-Wpointer-arith] for (int it = 0; word[it] != NULL; ++it) { ^ user.cpp: In function ‘int trieCount(TRIE*, char*)’: user.cpp:58:46: warning: NULL used in arithmetic [-Wpointer-arith] for (it = 0; root != NULL && word[it] != NULL; ++it) { ^ user.cpp:62:24: warning: NULL used in arithmetic [-Wpointer-arith] return word[it] != NULL || root == NULL ? 0 : root->apparitions; ^ user.cpp: In function ‘int prefixCount(TRIE*, char*)’: user.cpp:68:50: warning: NULL used in arithmetic [-Wpointer-arith] for (int it = 0; root != NULL && word[it] != NULL; ++it) { ^ user.cpp: In function ‘int main()’: user.cpp:91:13: warning: unused variable ‘a’ [-Wunused-variable] int a = 3; ^ user.cpp:85:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.in", "r", stdin); ^ user.cpp:86:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.out", "w", stdout); ^ user.cpp:89:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %s\n", &operation, word); ^