struct DouCirListNode{
 int data;
 DouCirListNode *prior, *next;

public:
 DouCirListNode():prior(NULL),next(NULL){}
 DouCirListNode(int elem, DouCirListNode *first=NULL,DouCirListNode *back=NULL):data(elem),prior(first),next(back){}
 ~DouCirListNode(){prior=NULL;   next=NULL;}
};

class  DouCirList{
private:
 DouCirListNode *first;
public:
 DouCirList():first(new DouCirListNode()){
  first->prior=first;
  first->next=first;
 }
 ~DouCirList(){
  MakeEmpty();
  delete first;
 }
 bool MakeEmpty();
 int  ListLength();
 bool IsEmpty();
 DouCirListNode* Find(int location);
 DouCirListNode* FindData(int elem);
    bool Insert(int location, int elem);
 void Remove(int location);
 bool RemoveAll(int elem);
 int GetData(int location);
 void ShowList();
};

bool DouCirList::MakeEmpty(){
 DouCirListNode *ptem=first->next, *pdel;
 while(ptem!=first){
  pdel=ptem;
  ptem=pdel->next;
  delete pdel;
 }
 first->next=first;
 first->prior=first;
 return 1;
}

bool DouCirList::IsEmpty(){
 return first->next==first;
}

int DouCirList::ListLength(){
 DouCirListNode *ptem=first;
 int count=0;
 while(ptem->next!=first){
  ptem=ptem->next;
  count++;
 }
 return count;
}

int DouCirList::GetData(int location){
 if(location<0){
  cout<<"sorry! the location must be over zero!"<<endl;
 }
 DouCirListNode *ptem=first;
 int i=0;
 while(ptem->next!=first&&i<location){
  i++;
  ptem=ptem->next;  
 }
 if(ptem==first)
  cout<<"sorry! can't get the data of the location!"<<endl;
 return ptem->data;
}

DouCirListNode* DouCirList::Find(int location){
 if(location<0){
  cout<<"sorry! can't find the node of the location!"<<endl;
  return NULL;
 }
 DouCirListNode *ptem=first->next;
 int i=0;
 while(ptem!=first&&i<location){
  i++;
  ptem=ptem->next;
 }
 if(ptem==first){
  cout<<"sorry! can't find the node of the location!"<<endl;
  return NULL;
 }
 return ptem;
}

DouCirListNode* DouCirList::FindData(int elem){
 DouCirListNode *ptem=first->next;
 while(ptem->data!=elem){
  if(ptem==first){
   cout<<"sorry! can't find the elem!"<<endl;
   return NULL;
   break;
  }
   ptem=ptem->next;
 }
 return ptem;
}

bool DouCirList::Insert(int location, int elem){
 if(location<0){
  cout<<"sorry! the location must be over 0!"<<endl;
  return 0;
 }
 DouCirListNode *ptem=first;
 int i=0;
 while(ptem->next!=first&&i<location){
  ptem=ptem->next;
  if(ptem==first){
   cout<<"sorry! can't find the correct location to insert!"<<endl;
   return 0;
   break;
  }
 }
 DouCirListNode *newnode=new DouCirListNode(elem);
 newnode->next=ptem->next;
 ptem->next->prior=newnode;
    newnode->prior=ptem;
 ptem->next=newnode;
 return 1;
}

void DouCirList::Remove(int location){
 if(location<0){
  cout<<"The n is out of boundary"<<endl;
  exit(1);
 }
 DouCirListNode *pmove=first,*pdel;
 for(int i=0;i<location;i++){   //find the position for delete
  pmove=pmove->next;
  if(pmove==first){
   cout<<"The n is out of boundary"<<endl;
   exit(1); 
  }
 }
 pdel=pmove;
 pmove->prior->next=pdel->next;
 pmove->next->prior=pdel->prior;
 delete pdel;

 /*if(location<0){
  cout<<"can't remove a node that not exist!"<<endl;
  return 0;
 }
 DouCirListNode *ptem=first, *pdel;
 for(int i=0;i<location;i++){
  ptem=ptem->next;
  if(ptem==first){
   cout<<"can't remove!"<<endl;
   return 0;
  }
 }
 pdel=ptem;
 ptem->prior->next = pdel->next;
 ptem->next->prior = pdel->prior;
 delete pdel;
 return 1;*/
}

bool DouCirList::RemoveAll(int elem){
 DouCirListNode *ptem = first->next, *pdel;
 while(ptem->next!=first){
  if(ptem->data==elem){
   pdel=ptem;
   ptem->prior->next=ptem->next;
   ptem->next->prior=ptem->prior;
   delete pdel;
  }
  ptem=ptem->next;
 }
 return 1;
}

void DouCirList::ShowList(){
 DouCirListNode *ptem=first;
 cout<<"first-->";
 while(ptem->next!=first){
  ptem=ptem->next;
  cout<<"-->";
  cout<<ptem->data;
 }
 cout<<"-->over"<<endl;
}

int main(){
return 0;

}

C++内存管理 有关VA_LIST的用法