本文主要和大家介绍php双向链表定义与用法,涉及php使用双向链表类封装双向链表定义、读取、删除、插入等相关操作技巧,需要的朋友可以参考下，希望能帮助到大家。
由于需要对一组数据多次进行移动操作，所以写个双向链表。但对php实在不熟悉，虽然测试各个方法没啥问题，就是不知道php语言深层的这些指针和unset有什么注意的地方，贴出来让大家教育吧。效率没测试....求谅解～
<?php
/**
* **双向链表
* @author zhiyuan12@
*/
/**
* 链表元素结点类
*/
class node_element {
public $pre = null; // 前驱
public $next = null; // 后继
public $key = null; // 元素键值
public $data = null; // 结点值
function __construct($key, $data) {
$this->key = $key;
$this->data = $data;
}
}
/**
* 双向链表类
*/
class doublelinkedlist {
private $head; // 头指针
private $tail; // 尾指针
private $current; // 当前指针
private $len; // 链表长度
function __construct() {
$this->head = self::_getnode ( null, null );
$this->curelement = $this->head;
$this->tail = $this->head;
$len = 0;
}
/**
* @ desc: 读取链表全部结点
*/
public function readall() {
$tmp = $this->head;
while ( $tmp->next !== null ) {
$tmp = $tmp->next;
var_dump ( $tmp->key, $tmp->data );
}
}
public function move($pos1, $pos2) {
$pos1node = $this->findposition ( $pos1 );
$pos2node = $this->findposition ( $pos2 );
if ($pos1node !== null && $pos2node !== null) {
$tmpkey = $pos1node->key;
$tmpdata = $pos1node->data;
$pos1node->key = $pos2node->key;
$pos1node->data = $pos2node->data;
$pos2node->key = $tmpkey;
$pos2node->data = $tmpdata;
return true;
}
return false;
}
/**
* @ desc: 在指定关键词删除结点
*
* @param : $key
* 指定位置的链表元素key
*/
public function delete($key) {
$pos = $this->find ( $key );
if ($pos !== null) {
$tmp = $pos;
$last = null;
$first = true;
while ( $tmp->next !== null && $tmp->next->key === $key ) {
$tmp = $tmp->next;
if (! $first) {
$this->delnode ( $last );
} else {
$first = false;
}
$last = $tmp;
}
if ($tmp->next !== null) {
$pos->pre->next = $tmp->next;
$tmp->next->pre = $pos->pre;
} else {
$pos->pre->next = null;
}
$this->delnode ( $pos );
$this->delnode ( $tmp );
}
}
/**
* @ desc: 在指定位置删除结点
*
* @param : $key
* 指定位置的链表元素key
*/
public function deleteposition($pos) {
$tmp = $this->findposition ( $pos );
if ($tmp === null) {
return true;
}
if ($tmp === $this->gettail ()) {
$tmp->pre->next = null;
$this->delnode ( $tmp );
return true;
}
$tmp->pre->next = $tmp->next;
$tmp->next->pre = $tmp->pre;
$this->delnode ( $tmp );
}
/**
* @ desc: 在指定键值之前插入结点
*
* @param : $key
* //指定位置的链表元素key
* @param : $data
* //要插入的链表元素数据
* @param : $flag
* //是否顺序查找位置进行插入
*/
public function insert($key, $data, $flag = true) {
$newnode = self::_getnode ( $key, $data );
$tmp = $this->find ( $key, $flag );
if ($tmp !== null) {
$newnode->pre = $tmp->pre;
$newnode->next = $tmp;
$tmp->pre = $newnode;
$newnode->pre->next = $newnode;
} else {
$newnode->pre = $this->tail;
$this->tail->next = $newnode;
$this->tail = $newnode;
}
$this->len ++;
}
/**
* @ desc: 在指定位置之前插入结点
*
* @param : $pos
* 指定插入链表的位置
* @param : $key
* 指定位置的链表元素key
* @param : $data
* 要插入的链表元素数据
*/
public function insertposition($pos, $key, $data) {
$newnode = self::_getnode ( $key, $data );
$tmp = $this->findposition ( $pos );
if ($tmp !== null) {
$newnode->pre = $tmp->pre;
$newnode->next = $tmp;
$tmp->pre = $newnode;
$newnode->pre->next = $newnode;
} else {
$newnode->pre = $this->tail;
$this->tail->next = $newnode;
$this->tail = $newnode;
}
$this->len ++;
return true;
}
/**
* @ desc: 根据key值查询指定位置数据
*
* @param : $key
* //指定位置的链表元素key
* @param : $flag
* //是否顺序查找
*/
public function find($key, $flag = true) {
if ($flag) {
$tmp = $this->head;
while ( $tmp->next !== null ) {
$tmp = $tmp->next;
if ($tmp->key === $key) {
return $tmp;
}
}
} else {
$tmp = $this->gettail ();
while ( $tmp->pre !== null ) {
if ($tmp->key === $key) {
return $tmp;
}
$tmp = $tmp->pre;
}
}
return null;
}
/**
* @ desc: 根据位置查询指定位置数据
*
* @param : $pos
* //指定位置的链表元素key
*/
public function findposition($pos) {
if ($pos <= 0 || $pos > $this->len)
return null;
if ($pos < ($this->len / 2 + 1)) {
$tmp = $this->head;
$count = 0;
while ( $tmp->next !== null ) {
$tmp = $tmp->next;
$count ++;
if ($count === $pos) {
return $tmp;
}
}
} else {
$tmp = $this->tail;
$pos = $this->len - $pos + 1;
$count = 1;
while ( $tmp->pre !== null ) {
if ($count === $pos) {
return $tmp;
}
$tmp = $tmp->pre;
$count ++;
}
}
return null;
}
/**
* @ desc: 返回链表头节点
*/
public function gethead() {
return $this->head->next;
}
/**
* @ desc: 返回链表尾节点
*/
public function gettail() {
return $this->tail;
}
/**
* @ desc: 查询链表节点个数
*/
public function getlength() {
return $this->len;
}
private static function _getnode($key, $data) {
$newnode = new node_element ( $key, $data );
if ($newnode === null) {
echo "new node fail!";
}
return $newnode;
}
private function delnode($node) {
unset ( $node );
$this->len --;
}
}
$mylist = new doublelinkedlist ();
$mylist->insert ( 1, "test1" );
$mylist->insert ( 2, "test2" );
$mylist->insert ( "2b", "test2-b" );
$mylist->insert ( 2, "test2-c" );
$mylist->insert ( 3, "test3" );
$mylist->insertposition ( 5, "t", "testt" );
$mylist->readall ();
echo "+++";
$mylist->deleteposition(0);
$mylist->readall ();
echo "..." . $mylist->getlength ();
var_dump ( $mylist->findposition ( 3 )->data );
?>
运行结果：
int(1)
string(5) "test1"
int(2)
string(7) "test2-c"
int(2)
string(5) "test2"
string(2) "2b"
string(7) "test2-b"
string(1) "t"
string(5) "testt"
int(3)
string(5) "test3"
+++int(1)
string(5) "test1"
int(2)
string(7) "test2-c"
int(2)
string(5) "test2"
string(2) "2b"
string(7) "test2-b"
string(1) "t"
string(5) "testt"
int(3)
string(5) "test3"
...6string(5) "test2"
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以上就是php双向链表基础详解的详细内容。