我查了一下help,选了下面这个函数
extern int UF_OBJ_cycle_objs_in_part (
tag_t part_tag, int type, tag_t * object );
tag_t part_tag Input Tag of part you wish to cycle
int type Input Type of object on which to cycle
tag_t * object Input/Output On input the object found
by the last call to this routine.
if this routine has not been called
yet, then set object=NULL_TAG
to start cycling.
On output the next object of the
type specified. If there is no
object, and the cycling is complete
a NULL_TAG is returned.