Compilare: user.cpp: In function ‘void adaugare(trie*&, char*)’: user.cpp:21:14: warning: NULL used in arithmetic [-Wpointer-arith] if(*s != NULL){ ^ user.cpp: In function ‘int sterge(trie*&, char*)’: user.cpp:33:15: warning: NULL used in arithmetic [-Wpointer-arith] if (*s == NULL){ ^ user.cpp: In function ‘int nrap(trie*, char*)’: user.cpp:58:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^ user.cpp: In function ‘void prefix(trie*, char*, int)’: user.cpp:66:34: warning: NULL used in arithmetic [-Wpointer-arith] if(r->f[*s-'a']==NULL || *s==NULL) ^