双向循环链表的插入和删除

#define OK 1
#define ERROR 0
typedef int Status;
typedef struct DuLNode
{
ElelmentType data;
struct DuLNode *prior;
struct DuLNode *next;
} * DuLinkedList;

DuLinkedList getElemp(DuLinkedList &L,int i) {
DuLinkedList p = L;
for(int j = i; j >0; j--) {
p = p->next;
}
return p;
}

/*在双链表第i个位置之前插入节点*/
Status insert_DuLinkedList(DuLinkedList &L,int i,ElelmentType e) {
DuLinkedList p,s;
if(!(p = getElemp(L,i)))//用于取得第i个位置的指针
return ERROR;
if(!(s = (DuLinkedList)malloc(sizeof(struct DuLNode))))
return ERROR;
s->data = e;
s->prior = p->prior;
s->prior->next = s;
s->next = p;
p->prior = s;
return OK;
}

/*在双链表上删除元素*/
ElelmentType Delete_Dulist(DuLinkedList &L, int i, ElelmentType &e) {
DuLinkedList p;
if(!(p = getElemp(L,i)))
return ERROR;
e = p->data;
p->prior->next = p-next;
p->next->prior = p->prior;
free(p);
return e;
}