双向链表也叫双链表，是链表的一种，它的每个数据结点中都有两个指针，分别指向直接后继和直接前驱。所以，从双向链表中的任意一个结点开始，都可以很方便地访问它的前驱结点和后继结点。一般我们都构造双向循环链表。

看了很久数据结构但是没有怎么用过，在网上看到了关于PHP的数据结构，学习了一下，与大家一起分享一下。上一次分享了《PHP小教程之实现链表》，这次来补充说一下双向链表，代码如下:

1. <?php 
2.         class Hero 
3.         { 
4.             public $pre=null; 
5.             public $no; 
6.             public $name; 
7.             public $next=null; 
8.             public function __construct($no='',$name='') 
9.             { 
10.                 $this->no=$no; 
11.                 $this->name=$name; 
12.             } 
13.             static public function addHero($head,$hero) 
14.             { 
15.                 $cur = $head; 
16.                 $isExist=false; 
17.                 //判断目前这个链表是否为空 
18.                 if($cur->next==null) 
19.                 { 
20.                     $cur->next=$hero; 
21.                     $hero->pre=$cur; 
22.                 } 
23.                 else 
24.                 { 
25.                     //如果不是空节点，则安排名来添加 
26.                     //找到添加的位置 
27.                     while($cur->next!=null) 
28.                     { 
29.                         if($cur->next->no > $hero->no) 
30.                         { 
31.                             break; 
32.                         } 
33.                         else if($cur->next->no == $hero->no) 
34.                         { 
35.                             $isExist=true; 
36.                             echo "<br>不能添加相同的编号"; 
37.                         } 
38.                         $cur=$cur->next; 
39.                     } 
40.                     if(!$isExist) 
41.                     { 
42.                         if($cur->next!=null) 
43.                         { 
44.                             $hero->next=$cur->next; 
45.                         } 
46.                         $hero->pre=$cur; 
47.                         if($cur->next!=null) 
48.                         { 
49.                             $hero->next->pre=$hero; 
50.                         } 
51.                         $cur->next=$hero;                    
52.                     } 
53.                 } 
54.             } 
55.             //遍历 
56.             static public function showHero($head) 
57.             { 
58.                 $cur=$head; 
59.                 while($cur->next!=null) 
60.                 { 
61.                     echo "<br>编号：".$cur->next->no."名字：".$cur->next->name; 
62.                     $cur=$cur->next; 
63.                 } 
64.             } 
65.             static public function delHero($head,$herono) 
66.             { 
67.                 $cur=$head; 
68.                 $isFind=false; 
69.                 while($cur!=null) 
70.                 { 
71.                     if($cur->no==$herono) 
72.                     { 
73.                         $isFind=true; 
74.                         break; 
75.                     } 
76.                     //继续找 
77.                     $cur=$cur->next; 
78.                 } 
79.                 if($isFind) 
80.                 { 
81.                     if($cur->next!=null) 
82.                     { 
83.                         $cur->next_pre=$cur->pre; 
84.                     } 
85.                     $cur->pre->next=$cur->next; 
86.                 } 
87.                 else 
88.                 { 
89.                     echo "<br>没有找到目标"; 
90.                 }                
91.             } 
92.         } 
93.         $head = new Hero(); 
94.         $hero1 = new Hero(1,'1111'); 
95.         $hero3 = new Hero(3,'3333'); 
96.         $hero2 = new Hero(2,'2222'); 
97.         Hero::addHero($head,$hero1); 
98.         Hero::addHero($head,$hero3); 
99.         Hero::addHero($head,$hero2); 
100.         Hero::showHero($head); 
101.         Hero::delHero($head,2); 
102.         Hero::showHero($head); 
103. ?> 

Tags: PHP双向链表

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