int hcreate(size_t nel);
ENTRY *hsearch(ENTRY item, ACTION action);
void hdestroy(void);
int hcreate_r(size_t nel, struct hsearch_data *htab);
int hsearch_r(ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab);
void hdestroy_r(struct hsearch_data *htab)