php id pid,关于无限分类的树状输出(id,name,pid)类型的数组

假设你有一个数组，其中包含了所有分类的信息，每个分类都有一个 ID、一个名称和一个父级分类的 ID。你可以使用递归函数来将这个数组转换成树状结构：

function buildTree(array $items, $parentId = 0) {
    $tree = [];
    foreach ($items as $item) {
        if ($item['pid'] == $parentId) {
            $children = buildTree($items, $item['id']);
            if ($children) {
                $item['children'] = $children;
            }
            $tree[] = $item;
        }
    }
    return $tree;
}

$categories = [
    ['id' => 1, 'name' => '分类1', 'pid' => 0],
    ['id' => 2, 'name' => '分类2', 'pid' => 0],
    ['id' => 3, 'name' => '分类3', 'pid' => 1],
    ['id' => 4, 'name' => '分类4', 'pid' => 1],
    ['id' => 5, 'name' => '分类5', 'pid' => 4],
    ['id' => 6, 'name' => '分类6', 'pid' => 2],
    ['id' => 7, 'name' => '分类7', 'pid' => 2],
];

$tree = buildTree($categories);
print_r($tree);

这个函数会递归遍历整个数组，以每个分类的父级 ID 作为参数进行调用。如果当前分类的父级 ID 匹配传入的父级 ID，那么就将当前分类加入到树状结构中，并递归调用函数来构建子树。最终，函数会返回根节点的数组，这个数组就是树状结构了。

输出结果：

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => 分类1
            [pid] => 0
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 3
                            [name] => 分类3
                            [pid] => 1
                            [children] => Array
                                (
                                )

                        )

                    [1] => Array
                        (
                            [id] => 4
                            [name] => 分类4
                            [pid] => 1
                            [children] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 5
                                            [name] => 分类5
                                            [pid] => 4
                                            [children] => Array
                                                (
                                                )

                                        )

                                )

                        )

                )

        )

    [1] => Array
        (
            [id] => 2
            [name] => 分类2
            [pid] => 0
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 6
                            [name] => 分类6
                            [pid] => 2
                            [children] => Array
                                (
                                )

                        )

                    [1] => Array
                        (
                            [id] => 7
                            [name] => 分类7
                            [pid] => 2
                            [children] => Array
                                (
                                )

                        )

                )

        )

)