双向链表的插入和删除算法描述

#include <iostream> 
using namespace std;
typedef int elemtype;
typedef int status;
typedef struct dulnode
{
  elemtype data;
  dulnode *prior;
  dulnode *next;
}dulnode,*dullinklist;
//插入结点
status listinsert_dul(dullinklist &l, int i, elemtype e)
{
  if (!(p = getelem_nul(l, i)))
    return -1;
  dullinklist s;
  s = new dulnode;
  s->data = e;
  s->prior = p->piror;
  p->piror->next = s;
  s->next = p;
  p->piror = s;
  return 0;
}
//删除结点
status listdelete_dul(dullinklist &l,int i,elemtype e)
{
  if (!(p = getelem_nul(l, i)))
    return -1;
  p->piror->next = p->next;
  p->next->piror = p->piror;
  delete p;
  return 0;
}