单项选择题
A.EOF B.非0值 C.0 D.NULL
A.*pt->y B.pt->x C.++pt->x D.(pt++)->x
A.q->next=r->next; p->next=r,r->next=q; B.p->next=r,q->next=r->next;r->next=q; C.q->next=r->next;r->next=q;p->next=r, D.r->next=q;P->next=r;q->next=r->next;