php三级分类

<?php
// 假设这是从数据库中获取的分类数据
$categories = [
    ['id' => 1, 'name' => '大类1', 'parent_id' => 0],
    ['id' => 2, 'name' => '中类1-1', 'parent_id' => 1],
    ['id' => 3, 'name' => '小类1-1-1', 'parent_id' => 2],
    ['id' => 4, 'name' => '大类2', 'parent_id' => 0],
    ['id' => 5, 'name' => '中类2-1', 'parent_id' => 4],
];

// 构建分类树
function buildTree($categories, $parentId = 0) {
    $tree = [];
    foreach ($categories as $category) {
        if ($category['parent_id'] == $parentId) {
            $children = buildTree($categories, $category['id']);
            if ($children) {
                $category['children'] = $children;
            }
            $tree[] = $category;
        }
    }
    return $tree;
}

$tree = buildTree($categories);

// 输出分类树
function printTree($tree, $level = 0) {
    foreach ($tree as $item) {
        echo str_repeat("  ", $level) . $item['name'] . "\n";
        if (isset($item['children'])) {
            printTree($item['children'], $level + 1);
        }
    }
}

printTree($tree);
?>