<span style="font-size:18px;"><strong>//代码为自己编写，可能有问题，欢迎大家留言指正！</strong></span>

<span style="font-size:18px;"><strong></strong></span>

#include <iostream>
#include <string>
using namespace std;
typedef struct dnode
{
	int val;
	dnode *prior;
	dnode *next;
}dnode;

dnode * create();
void traverse(dnode *pHead);
bool insert(dnode *pHead,int pos,int val);
bool del(dnode *pHead,int pos,int &val);
void inverse(dnode *pHead);
void main()
{
	dnode *pHead = create();
	traverse(pHead);
	insert(pHead,3,5);
	traverse(pHead);
	int val;
	del(pHead,4,val);
	cout<<val<<endl;
	traverse(pHead);
	inverse(pHead);
	//traverse(pHead);
}

//建立循环双链表
dnode *create()
{
	dnode *pHead = new dnode,*pTail;
	pTail = pHead;
	pTail->next = pHead;
	//pHead->prior = pTail;
	for (int i =0;i<4;i++)
	{
		dnode *pNew = new dnode;
		pNew->val = i+1;
		pNew->next = pTail->next;
		pTail->next = pNew;
		pNew->prior = pTail;
		pTail = pNew;
	}
	pHead->prior = pTail;
	return pHead;
}

void traverse(dnode *pHead)
{
	dnode *p =pHead->next;
	while (p != pHead)
	{
		cout<<p->val<<" ";
		p = p->next; 
	}
	cout<<endl;
}

bool insert(dnode *pHead,int pos,int val)
{
	dnode *p = pHead,*q;
	int i = 1;
	while (p->next != pHead && i < pos) //找到pos-1个节点（不包括头结点）
	{
		++i;
		p = p->next;
	}

	if (i > pos || p->next == pHead)
	{
		return false;
	}
	dnode *pNew = new dnode;
	q = p->next; 
	pNew->val = val;
	p->next = pNew;
	pNew->prior = p;
	pNew->next = q;
	q->prior = pNew;
	return true;
}

bool del(dnode *pHead,int pos,int &val)
{
	dnode *p = pHead,*q;
	int i = 1;
	while (p->next != pHead && i < pos) //找到pos-1个节点（不包括头结点）
	{
		++i;
		p = p->next;
	}

	if (i > pos || p->next == pHead)
	{
		return false;
	}
    q = p->next; //q为要删除的节点
 	val = q->val;
 	p->next = q->next;
 	q->next->prior = p;
 	delete q;
	return true;
}
//逆序输出
void inverse(dnode *pHead)
{
	dnode *p = pHead->prior; //p指向最后一个节点
	while (p != pHead)
	{
		cout<<p->val<<" ";
		p = p->prior;
	}
	cout<<endl;
}