PHP多级分类代码——树形结构

//方法一：
function genTree5($items) {
    foreach ($items as $key=>$item)
        $items[$item['pid']]['son'][$item['id']] = &$items[$key];
    return isset($items[0]['son']) ? $items[0]['son'] : array();
}

//方法二：
function genTree9($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'),//注意id值一定要跟键值对应
    2 => array('id' => 2, 'pid' => 1, 'name' => '芜湖市'),
    3 => array('id' => 3, 'pid' => 2, 'name' => '弋江区'),
    4 => array('id' => 4, 'pid' => 3, 'name' => '花津南路'),
    5 => array('id' => 5, 'pid' => 4, 'name' => '中梦科技')
);

echo '<pre>';
print_r(genTree5($items));
print_r(genTree9($items));