在进行无限极分类中最常用的算法就是“递归”，熟悉PHP语言的朋友肯定知道，PHP不擅长递归 ,而且递归次数有限（100次左右，因操作系统和配置而异）。
所以本文将会给大家带来几种不使用递归实现无限级分类的代码。供大家来学习使用。
第一种：
无限级分类在开发中经常使用，例如：部门结构、文章分类。无限级分类的难点在于“输出”和“查询”，例如
将文章分类输出为ff6d136ddc5fdfeffaf53ff6ee95f185列表形式；
查找分类A下面所有分类包含的文章。
1.实现原理
几种常见的实现方法，各有利弊。其中“改进前序遍历树”数据结构，便于输出和查询，但是在移动分类和常规理解上有些复杂。
2.数据结构
<?php $list = array( array('id'=>1, 'fid'=>0, 'title' => '中国'), array('id'=>2, 'fid'=>1, 'title' => '江苏'), array('id'=>3, 'fid'=>1, 'title' => '安徽'), array('id'=>4, 'fid'=>8, 'title' => '江阴'), array('id'=>5, 'fid'=>3, 'title' => '芜湖'), array('id'=>6, 'fid'=>3, 'title' => '合肥'), array('id'=>7, 'fid'=>3, 'title' => '蚌埠'), array('id'=>8, 'fid'=>8, 'title' => '无锡') ); ?>
由于所有的递归均可以使用循环实现，本文根据PHP语言特点编写了一套关于“无限级”分类的函数，相比递归实现而言效率更高。
3.输出ul列表形式
将上述数据输出为下面的HTML
<ul> <li class="first-child"> <p>江苏</p> <ul> <li class="first-child last-child"> <p>无锡</p> <ul> <li class="first-child last-child"> <p>江阴</p> </li> </ul> </li> </ul> </li> <li class="last-child"> <p>安徽</p> <ul> <li class="first-child"><p>芜湖</p></li> <li><p>合肥</p></li> <li class="last-child"><p>蚌埠</p></li> </ul> </li> </ul>
这种HTML结构在前端使用（使用JavaScript和CSS构造可折叠树）十分方便。具体实现程序如下：
<ul><?php echo get_tree_ul($list, 1); ?></ul>
4.输出option列表形式
<select> <option value="2">江苏</option> <option value="8"> 无锡</option> <option value="4"> 江阴</option> <option value="3">安徽</option> <option value="5"> 芜湖</option> <option value="6"> 合肥</option> <option value="7"> 蚌埠</option> </select>
具体实现程序如下：
<select>
<?php
// get_tree_option()返回数组，并为每个元素增加了“深度”（即depth）列，直接输出即可
$options = get_tree_option($list, 1);
foreach($options as $op) {
echo '<option value="' . $op['id'] .'">' . str_repeat(" ", $op['depth'] * 4) . $op['title'] . '<;/option>';
}
?>
<;/select>5. 查找某一分类的所有子类
<?php $children = get_tree_child($list, 0); echo implode(',', $children); // 输出：1,3,2,7,6,5,8,4 ?>
6. 查找某一分类的所有父类
<?php $children = get_tree_parent($list, 4); echo implode(',', $children); //8, 2, 10 ?>
7. 相关函数
<?php
function get_tree_child($data, $fid) {
$result = array();
$fids = array($fid);
do {
$cids = array();
$flag = false;
foreach($fids as $fid) {
for($i = count($data) - 1; $i >=0 ; $i--) {
$node = $data[$i];
if($node['fid'] == $fid) {
array_splice($data, $i , 1);
$result[] = $node['id'];
$cids[] = $node['id'];
$flag = true;
}
}
}
$fids = $cids;
} while($flag === true);
return $result;
}
function get_tree_parent($data, $id) {
$result = array();
$obj = array();
foreach($data as $node) {
$obj[$node['id']] = $node;
}
$value = isset($obj[$id]) ? $obj[$id] : null;
while($value) {
$id = null;
foreach($data as $node) {
if($node['id'] == $value['fid']) {
$id = $node['id'];
$result[] = $node['id'];
break;
}
}
if($id === null) {
$result[] = $value['fid'];
}
$value = isset($obj[$id]) ? $obj[$id] : null;
}
unset($obj);
return $result;
}
function get_tree_ul($data, $fid) {
$stack = array($fid);
$child = array();
$added_left = array();
$added_right= array();
$html_left = array();
$html_right = array();
$obj = array();
$loop = 0;
foreach($data as $node) {
$pid = $node['fid'];
if(!isset($child[$pid])) {
$child[$pid] = array();
}
array_push($child[$pid], $node['id']);
$obj[$node['id']] = $node;
}
while (count($stack) > 0) {
$id = $stack[0];
$flag = false;
$node = isset($obj[$id]) ? $obj[$id] : null;
if (isset($child[$id])) {
$cids = $child[$id];
$length = count($cids);
for($i = $length - 1; $i >= 0; $i--) {
array_unshift($stack, $cids[$i]);
}
$obj[$cids[$length - 1]]['isLastChild'] = true;
$obj[$cids[0]]['isFirstChild'] = true;
$flag = true;
}
if ($id != $fid && $node && !isset($added_left[$id])) {
if(isset($node['isFirstChild']) && isset($node['isLastChild'])) {
$html_left[] = '<li class="first-child last-child">';
} else if(isset($node['isFirstChild'])) {
$html_left[] = '<li class="first-child">';
} else if(isset($node['isLastChild'])) {
$html_left[] = '<li class="last-child">';
} else {
$html_left[] = '<li>';
}
$html_left[] = ($flag === true) ? "<p>{$node['title']}</p><ul>" : "<p>{$node['title']}</p>";
$added_left[$id] = true;
}
if ($id != $fid && $node && !isset($added_right[$id])) {
$html_right[] = ($flag === true) ? '</ul></li>' : '</li>';
$added_right[$id] = true;
}
if ($flag == false) {
if($node) {
$cids = $child[$node['fid']];
for ($i = count($cids) - 1; $i >= 0; $i--) {
if ($cids[$i] == $id) {
array_splice($child[$node['fid']], $i, 1);
break;
}
}
if(count($child[$node['fid']]) == 0) {
$child[$node['fid']] = null;
}
}
array_push($html_left, array_pop($html_right));
array_shift($stack);
}
$loop++;
if($loop > 5000) return $html_left;
}
unset($child);
unset($obj);
return implode('', $html_left);
}
function get_tree_option($data, $fid) {
$stack = array($fid);
$child = array();
$added = array();
$options = array();
$obj = array();
$loop = 0;
$depth = -1;
foreach($data as $node) {
$pid = $node['fid'];
if(!isset($child[$pid])) {
$child[$pid] = array();
}
array_push($child[$pid], $node['id']);
$obj[$node['id']] = $node;
}
while (count($stack) > 0) {
$id = $stack[0];
$flag = false;
$node = isset($obj[$id]) ? $obj[$id] : null;
if (isset($child[$id])) {
for($i = count($child[$id]) - 1; $i >= 0; $i--) {
array_unshift($stack, $child[$id][$i]);
}
$flag = true;
}
if ($id != $fid && $node && !isset($added[$id])) {
$node['depth'] = $depth;
$options[] = $node;
$added[$id] = true;
}
if($flag == true){
$depth++;
} else {
if($node) {
for ($i = count($child[$node['fid']]) - 1; $i >= 0; $i--) {
if ($child[$node['fid']][$i] == $id) {
array_splice($child[$node['fid']], $i, 1);
break;
}
}
if(count($child[$node['fid']]) == 0) {
$child[$node['fid']] = null;
$depth--;
}
}
array_shift($stack);
}
$loop++;
if($loop > 5000) return $options;
}
unset($child);
unset($obj);
return $options;
}
?>第二种：
这是使用TP来制作的无限级分类。
算法复杂度为T(n)=O(2n),只遍历两次数组.
关键代码其实只有一行
$return[$v['pid']]['child'][$v['id']] = &$return[$k];
但是为了实现较为复杂的扩展,这里添加一些额外的信息
//索引要和ID一致,这不是废话么
//pid是父元素
//不要出现死循环嵌套,就是AB互为父子
//不要出现相同name
$list[0]=['id'=>0,'pid'=>-1,'name'=>'A@0'];//-1用于后面的根目录判断
$list[1]=['id'=>1,'pid'=>0,'name'=>'A@1'];
$list[2]=['id'=>2,'pid'=>0,'name'=>'A@2'];
$list[3]=['id'=>3,'pid'=>2,'name'=>'A@3'];
$list[4]=['id'=>4,'pid'=>3,'name'=>'A@4'];
$list[5]=['id'=>5,'pid'=>0,'name'=>'A@5'];
$list[6]=['id'=>6,'pid'=>1,'name'=>'A@6'];
//先初始化目录
$return=[];
foreach($list as $v)
$return[$v['name']]=[];
//将每个目录与父目录进行拼接,并找到根目录
foreach($list as $k=>$v)
{
if($v['pid']>=0)
$return[$list[$v['pid']]['name']][$v['name']]=&$return[$v['name']];
else
$parent=$v['name'];
}
//打印根目录
print_r($return[$parent]);输出1
Array(
[A@1] => Array
(
[A@6] => Array
(
)
)
[A@2] => Array
(
[A@3] => Array
(
[A@4] => Array
(
)
)
)
[A@5] => Array
(
)
)代码2
/**
* Created by PhpStorm.
* User: Nikaidou-Shinku
* Date: 16/9/14
* Time: 17:12
*/
$list[] = ['id' => 0, 'pid' => -1, 'name' => 'A@0'];//-1用于后面的根目录判断
$list[] = ['id' => 1, 'pid' => 0, 'name' => 'A@1'];
$list[] = ['id' => 2, 'pid' => 0, 'name' => 'A@2'];
$list[] = ['id' => 3, 'pid' => 2, 'name' => 'A@3'];
$list[] = ['id' => 4, 'pid' => 3, 'name' => 'A@4'];
$list[] = ['id' => 5, 'pid' => 0, 'name' => 'A@5'];
$list[] = ['id' => 6, 'pid' => 1, 'name' => 'A@6'];
//先初始化目录
$return = [];
$parent = '';
foreach ($list as $v)
$return[$v['id']] = [
'id' => $v['id'],
'name' => $v['name'],
'pid' => $v['pid'],
'child' => '',
];
//将每个目录与父目录进行拼接,并找到根目录
foreach ($return as $k => $v) {
if ($v['pid'] >= 0)
$return[$v['pid']]['child'][$v['id']] = &$return[$k];
else
$parent = &$return[$k];
}
//打印根目录
var_export($parent);输出2
$aa=[
'id' => 0,
'name' => 'A@0',
'pid' => -1,
'child' =>
[
1 =>
[
'id' => 1,
'name' => 'A@1',
'pid' => 0,
'child' =>
[
6 =>
[
'id' => 6,
'name' => 'A@6',
'pid' => 1,
'child' => '',
],
],
],
2 =>
[
'id' => 2,
'name' => 'A@2',
'pid' => 0,
'child' =>
[
3 =>
[
'id' => 3,
'name' => 'A@3',
'pid' => 2,
'child' =>
[
4 =>
[
'id' => 4,
'name' => 'A@4',
'pid' => 3,
'child' => '',
],
],
],
],
],
5 =>
[
'id' => 5,
'name' => 'A@5',
'pid' => 0,
'child' => '',
],
],
]第三种：
接下来这个无限级分类更为的简单。可以简化成使用5行代码就可以完成。
function generateTree($items){
$tree = array();
foreach($items as $item){
if(isset($items[$item['pid']])){
$items[$item['pid']]['son'][] = &$items[$item['id']];
}else{
$tree[] = &$items[$item['id']];
}
}
return $tree;
}
$items = array(
1 => array('id' => 1, 'pid' => 0, 'name' => '安徽省'),
2 => array('id' => 2, 'pid' => 0, 'name' => '浙江省'),
3 => array('id' => 3, 'pid' => 1, 'name' => '合肥市'),
4 => array('id' => 4, 'pid' => 3, 'name' => '长丰县'),
5 => array('id' => 5, 'pid' => 1, 'name' => '安庆市'),
);
print_r(generateTree($items));可以看到下面打印的结果：
Array
(
[0] => Array
(
[id] => 1
[pid] => 0
[name] => 安徽省
[son] => Array
(
[0] => Array
(
[id] => 3
[pid] => 1
[name] => 合肥市
[son] => Array
(
[0] => Array
(
[id] => 4
[pid] => 3
[name] => 长丰县
)
)
)
[1] => Array
(
[id] => 5
[pid] => 1
[name] => 安庆市
)
)
)
[1] => Array
(
[id] => 2
[pid] => 0
[name] => 浙江省
)
)上面生成树方法还可以精简到5行：
function generateTree($items){
foreach($items as $item)
$items[$item['pid']]['son'][$item['id']] = &$items[$item['id']];
return isset($items[0]['son']) ? $items[0]['son'] : array();
}但是上面的代码有个问题就是对数据库结构有点要求，每个节点要指明其父节点是谁，虽然实用性不高，但是还是能给大家带来启发，学习下不同类型的无限级分类。
Working with Flash Session Data in LaravelMar 12, 2025 pm 05:08 PMLaravel simplifies handling temporary session data using its intuitive flash methods. This is perfect for displaying brief messages, alerts, or notifications within your application. Data persists only for the subsequent request by default: $request-
Build a React App With a Laravel Back End: Part 2, ReactMar 04, 2025 am 09:33 AMThis is the second and final part of the series on building a React application with a Laravel back-end. In the first part of the series, we created a RESTful API using Laravel for a basic product-listing application. In this tutorial, we will be dev
cURL in PHP: How to Use the PHP cURL Extension in REST APIsMar 14, 2025 am 11:42 AMThe PHP Client URL (cURL) extension is a powerful tool for developers, enabling seamless interaction with remote servers and REST APIs. By leveraging libcurl, a well-respected multi-protocol file transfer library, PHP cURL facilitates efficient execution of various network protocols, including HTTP, HTTPS, and FTP. This extension offers granular control over HTTP requests, supports multiple concurrent operations, and provides built-in security features.
Simplified HTTP Response Mocking in Laravel TestsMar 12, 2025 pm 05:09 PMLaravel provides concise HTTP response simulation syntax, simplifying HTTP interaction testing. This approach significantly reduces code redundancy while making your test simulation more intuitive. The basic implementation provides a variety of response type shortcuts: use Illuminate\Support\Facades\Http; Http::fake([ 'google.com' => 'Hello World', 'github.com' => ['foo' => 'bar'], 'forge.laravel.com' =>
12 Best PHP Chat Scripts on CodeCanyonMar 13, 2025 pm 12:08 PMDo you want to provide real-time, instant solutions to your customers' most pressing problems? Live chat lets you have real-time conversations with customers and resolve their problems instantly. It allows you to provide faster service to your custom
Notifications in LaravelMar 04, 2025 am 09:22 AMIn this article, we're going to explore the notification system in the Laravel web framework. The notification system in Laravel allows you to send notifications to users over different channels. Today, we'll discuss how you can send notifications ov
Explain the concept of late static binding in PHP.Mar 21, 2025 pm 01:33 PMArticle discusses late static binding (LSB) in PHP, introduced in PHP 5.3, allowing runtime resolution of static method calls for more flexible inheritance.Main issue: LSB vs. traditional polymorphism; LSB's practical applications and potential perfo
PHP Logging: Best Practices for PHP Log AnalysisMar 10, 2025 pm 02:32 PMPHP logging is essential for monitoring and debugging web applications, as well as capturing critical events, errors, and runtime behavior. It provides valuable insights into system performance, helps identify issues, and supports faster troubleshoot
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.
