$items = array( array('id'=>1,'pid'=>0,'name'=>'一级11'), array('id'=>2,'pid'=>0,'name'=>'一级12'), array('id'=>3,'pid'=>1,'name'=>'二级21'), array('id'=>4,'pid'=>3,'name'=>'三级31'), array('id'=>5,'pid'=>1,'name'=>'二级22'), array('id'=>6,'pid'=>3,'name'=>'三级32'), array('id'=>7,'pid'=>6,'name'=>'四级41'), ); $i = 0; function formatTree($arr, $pid = 0){ $tree = array(); $temp = array(); global $i; if($arr){ foreach($arr as $k=>$v){ if($v['pid'] == $pid){// $temp = formatTree($arr, $v['id']); $temp && $v['son'] = $temp; $tree[] = $v; } } } return $tree; } print_r(formatTree($items));

function genTree($items) {     $tree = array(); //格式化好的树     foreach ($items as $item)         if (isset($items[$item['pid']])){             $items[$item['pid']]['son'][] = &$items[$item['id']];         }         else{             $tree[] = &$items[$item['id']];         }     return $tree; } $items = array(     1 => array('id' => 1, 'pid' => 0, 'name' => '一级11'),     2 => array('id' => 2, 'pid' => 1, 'name' => '二级21'),     3 => array('id' => 3, 'pid' => 1, 'name' => '二级23'),     4 => array('id' => 4, 'pid' => 9, 'name' => '三级31'),     5 => array('id' => 5, 'pid' => 4, 'name' => '四级43'),     6 => array('id' => 6, 'pid' => 9, 'name' => '三级32'),     7 => array('id' => 7, 'pid' => 4, 'name' => '四级41'),     8 => array('id' => 8, 'pid' => 4, 'name' => '四级42'),     9 => array('id' => 9, 'pid' => 1, 'name' => '二级25'),     10 => array('id' => 10, 'pid' => 11, 'name' => '二级22'),     11 => array('id' => 11, 'pid' => 0, 'name' => '一级12'),     12 => array('id' => 12, 'pid' => 11, 'name' => '二级24'),     13 => array('id' => 13, 'pid' => 4, 'name' => '四级44'),     14 => array('id' => 14, 'pid' => 1, 'name' => '二级26'),     15 => array('id' => 15, 'pid' => 8, 'name' => '五级51'),     16 => array('id' => 16, 'pid' => 8, 'name' => '五级52'),     17 => array('id' => 17, 'pid' => 8, 'name' => '五级53'),     18 => array('id' => 18, 'pid' => 16, 'name' => '六级64'), ); print_r(genTree($items));