双向循环链表的数据添加为一个环形，重点在于对链表节点的连接；

 相信配合代码大家会更加清晰的理解；核心就是先连后断。

#include<stdio.h>
#include<stdlib.h>
struct node
{
	int data;
	struct node* pnext;
	struct node* Ppore;
};

void endadd(struct node* blankhead, int* count, int adddata);


int main()
{
    //创造空头
	struct node blankhead;
	blankhead.data = 0;
	blankhead.pnext = &blankhead;
	blankhead.Ppore = &blankhead;
	int count = 0;
	endadd(&blankhead, &count, 9);
	endadd(&blankhead, &count, 8);
	endadd(&blankhead, &count, 7);
	return 0;
	system("pause>0");
}
void endadd(struct node * blankhead, int* count, int adddata)

{
	if (NULL == blankhead)
		return;
	struct node* ptemp = (struct node*)malloc(sizeof(struct node));
	if (NULL == ptemp)
		return;
    //连接
	ptemp->data = adddata;
	ptemp->pnext = NULL;
	ptemp->Ppore = NULL;
	ptemp->Ppore = blankhead->Ppore;
	ptemp->pnext = blankhead;
	//后断（有顺序）
	blankhead->Ppore->pnext = ptemp;
	blankhead->Ppore = ptemp;
	(*count)++;



}