php 怎麼實作單鍊錶

php實作單鍊錶的方法：先寫出鍊錶節點的類別；然後在鍊錶中也定義兩個方法，分別是插入和刪除；接著取得鍊錶長度並加入節點資料；最後取得節點名字並進行刪除或更新操作即可。

本文操作環境：Windows7系統、PHP7.1、Dell G3電腦。

用PHP實作的單鍊錶

單鍊錶顧名思義就是一個鍊式資料結構，它有一個表頭，除了最後一個節點外，所有節點都有其後繼節點。如下圖。

首先，我們寫出鍊錶節點的類別。單鍊錶中的每一個節點，都保存其資料域和後輪驅動指標

//链表节点 
class node { 
    public $id; //节点id 
    public $name; //节点名称 
    public $next; //下一节点 
   
    public function __construct($id, $name) { 
        $this->id = $id; 
        $this->name = $name; 
        $this->next = null; 
    } 
}

鍊錶中還有兩個特別重要的方法，插入和刪除。插入需要找到插入的位置，把前一個元素的next指標指向被插入的節點，並將被插入節點的next指標指向後一個節點，如下圖左側所示。而刪除則是把前一個節點的next指標指向後一個節點，並傳回被刪除元素的資料內容，如下圖右側所示。

 

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//单链表 
class singelLinkList { 
    private $header; //链表头节点 
   
    //构造方法 
    public function __construct($id = null, $name = null) { 
        $this->header = new node ( $id, $name, null ); 
    } 
 
    //获取链表长度 
    public function getLinkLength() { 
        $i = 0; 
        $current = $this->header; 
        while ( $current->next != null ) { 
            $i ++; 
            $current = $current->next; 
        } 
        return $i; 
    } 
 
    //添加节点数据 
    public function addLink($node) { 
        $current = $this->header; 
        while ( $current->next != null ) { 
            if ($current->next->id > $node->id) { 
                break; 
            } 
            $current = $current->next; 
        } 
        $node->next = $current->next; 
        $current->next = $node; 
    } 
 
    //删除链表节点 
    public function delLink($id) { 
        $current = $this->header; 
        $flag = false; 
        while ( $current->next != null ) { 
            if ($current->next->id == $id) { 
                $flag = true; 
                break; 
            } 
            $current = $current->next; 
        } 
        if ($flag) { 
            $current->next = $current->next->next; 
        } else { 
            echo "未找到id=" . $id . "的节点！<br>"; 
        } 
    }
 
    //判断连表是否为空
    public function isEmpty(){
            return $this->header == null;
    }
 
    //清空链表
    public function clear(){
            $this->header = null;
    } 
 
    //获取链表 
    public function getLinkList() { 
        $current = $this->header; 
        if ($current->next == null) { 
            echo ("链表为空!"); 
            return; 
        } 
        while ( $current->next != null ) { 
            echo &#39;id:&#39; . $current->next->id . &#39;   name:&#39; . $current->next->name . "<br>"; 
            if ($current->next->next == null) { 
                break; 
            } 
            $current = $current->next; 
        } 
    } 
 
    //获取节点名字 
    public function getLinkNameById($id) { 
        $current = $this->header; 
        if ($current->next == null) { 
            echo "链表为空!"; 
            return; 
        } 
        while ( $current->next != null ) { 
            if ($current->id == $id) { 
                break; 
            } 
            $current = $current->next; 
        } 
        return $current->name; 
    } 
 
    //更新节点名称 
    public function updateLink($id, $name) { 
        $current = $this->header; 
        if ($current->next == null) { 
            echo "链表为空!"; 
            return; 
        } 
        while ( $current->next != null ) { 
            if ($current->id == $id) { 
                break; 
            } 
            $current = $current->next; 
        } 
        return $current->name = $name; 
    } 
}
$lists = new singelLinkList (); 
$lists->addLink ( new node ( 5, &#39;eeeeee&#39; ) ); 
$lists->addLink ( new node ( 1, &#39;aaaaaa&#39; ) ); 
$lists->addLink ( new node ( 6, &#39;ffffff&#39; ) ); 
$lists->addLink ( new node ( 4, &#39;dddddd&#39; ) ); 
$lists->addLink ( new node ( 3, &#39;cccccc&#39; ) ); 
$lists->addLink ( new node ( 2, &#39;bbbbbb&#39; ) ); 
$lists->getLinkList (); 
echo "<br>-----------删除节点--------------<br>"; 
$lists->delLink ( 5 ); 
$lists->getLinkList ();
echo "<br>-----------更新节点名称--------------<br>"; 
$lists->updateLink ( 3, "222222" ); 
$lists->getLinkList ();
echo "<br>-----------获取节点名称--------------<br>"; 
echo $lists->getLinkNameById ( 5 );
echo "<br>-----------获取链表长度--------------<br>"; 
echo $lists->getLinkLength ();

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