Compilare: user.cpp: In function ‘void initialize(trie*, char*, int)’: user.cpp:35:15: warning: NULL used in arithmetic [-Wpointer-arith] if (*s == NULL) { ^ user.cpp: In function ‘void query(trie*, char*, int)’: user.cpp:56:13: warning: NULL used in arithmetic [-Wpointer-arith] if(*s == NULL) { ^ user.cpp: In function ‘int main()’: user.cpp:81:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < strlen(substring[1]); i++) ^ user.cpp:88:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < strlen(substring[i]); j++) ^ user.cpp:84:9: warning: unused variable ‘lastHASH’ [-Wunused-variable] int lastHASH = 0; ^