typedef struct node
 {
   int x;
   struct node *prior,*next;
 }DLNode;

//創(chuàng)建雙向鏈表
DLNode *create_DList()
{
  DLNode *p,*h,*l;
  int n,i,x;
  h = (DLNode *)malloc(sizeof(DLNode));
  h->prior = h;　　　　//當(dāng)空的雙向鏈表就像上圖那樣前驅(qū)和后驅(qū)都會(huì)指向自己；
  h->next = h;
  p = h;
  printf("請(qǐng)輸入需要?jiǎng)?chuàng)建雙向鏈表的長(zhǎng)度：");
  scanf("%d",&n);
  for(i = 0; i < n; i++)
  {
    printf("請(qǐng)輸入第%d個(gè)數(shù)",i+1);
    scanf("%d",&x);
    l = (DLNode *)malloc(sizeof(DLNode));
    l->x = x;
    p->next = l;
    l->prior = p;
    l->next = h;　　　　　//注意，l->next鏈接的是頭節(jié)點(diǎn)，　
    h->prior = l;　　　　//而頭結(jié)點(diǎn)的前驅(qū)是l。 這樣便構(gòu)成了一個(gè)循環(huán)的雙向鏈表
    p = l;
  }
  return(h);　　//不要忘記返回鏈表
}

void out_DList(DLNode *l)
{
  DLNode *p;
  int i;
  p = l;
  p = p->next;
  while(p!=l)　　//注意條件發(fā)生了變化
  {
    printf("%5d",p->x);
    p = p->next;　　//不要忘記讓p指向下一個(gè)節(jié)點(diǎn)；
  }
}

#include<stdio.h>
#include <stdlib.h>

typedef struct node
{
  int x;
  struct node *prior,*next;
}DLNode;

//函數(shù)聲明
DLNode *create_DList();
void out_DList(DLNode *l);

main()
{
  DLNode *l;
  l = create_DList();
  printf("創(chuàng)建成功！");
  out_DList(l);
}

//讀取雙向鏈表
void out_DList(DLNode *l)
{
  DLNode *p;
  int i;
  p = l;
  p = p->next;
  while(p!=l)
  {
    printf("%5d",p->x);
    p = p->next;
  }
}


//創(chuàng)建雙向鏈表
DLNode *create_DList()
{
  DLNode *p,*h,*l;
  int n,i,x;
  h = (DLNode *)malloc(sizeof(DLNode));
  h->prior = h;
  h->next = h;
  p = h;
  printf("請(qǐng)輸入需要?jiǎng)?chuàng)建雙向鏈表的長(zhǎng)度：");
  scanf("%d",&n);
  for(i = 0; i < n; i++)
  {
    printf("請(qǐng)輸入第%d個(gè)數(shù)",i+1);
    scanf("%d",&x);
    l = (DLNode *)malloc(sizeof(DLNode));
    l->x = x;
    p->next = l;
    l->prior = p;
    l->next = h;
    h->prior = l;
    p = l;
  }
  return(h);
}