PHP無限級分類實現（遞迴+非遞迴）____PHP

<?php/** * Created by PhpStorm. * User: qishou * Date: 15-8-2 * Time: 上午12:00 *///準備數組，代替從資料庫中檢索出的資料(共有三個必須欄位id,name,pid)header("content-type:text/html;charset=utf-8");$categories = array(    array('id'=>1,'name'=>'電腦','pid'=>0),    array('id'=>2,'name'=>'手機','pid'=>0),    array('id'=>3,'name'=>'筆記本','pid'=>1),    array('id'=>4,'name'=>'台式機','pid'=>1),    array('id'=>5,'name'=>'智能機','pid'=>2),    array('id'=>6,'name'=>'功能機','pid'=>2),    array('id'=>7,'name'=>'超級本','pid'=>3),    array('id'=>8,'name'=>'遊戲本','pid'=>3),);/*======================非遞迴實現========================*/$tree = array();//第一步，將分類id作為數組key,並建立children單元foreach($categories as $category){    $tree[$category['id']] = $category;    $tree[$category['id']]['children'] = array();}//第二步，利用引用，將每個分類添加到父類children數組中，這樣一次遍曆即可形成樹形結構。foreach($tree as $key=>$item){    if($item['pid'] != 0){        $tree[$item['pid']]['children'][] = &$tree[$key];//注意：此處必須傳引用否則結果不對        if($tree[$key]['children'] == null){            unset($tree[$key]['children']); //如果children為空白，則刪除該children元素（可選）        }    }}////第三步，刪除無用的非根節點資料foreach($tree as $key=>$category){    if($category['pid'] != 0){        unset($tree[$key]);    }}print_r($tree);/*======================遞迴實現========================*/$tree = $categories;function get_attr($a,$pid){    $tree = array();                                //每次都聲明一個新數組用來放子項目    foreach($a as $v){        if($v['pid'] == $pid){                      //匹配子記錄            $v['children'] = get_attr($a,$v['id']); //遞迴擷取子記錄            if($v['children'] == null){                unset($v['children']);             //如果子項目為空白則unset()進行刪除，說明已經到該分支的最後一個元素了（可選）            }            $tree[] = $v;                           //將記錄存入新數組        }    }    return $tree;                                  //返回新數組}echo "<br/><br/><br/>";print_r(get_attr($tree,0));