I am sorry for the problem of limiting the number of recursive traversal times. First of all, I declare that the method I think is not good. if you think recursion is good, try it.

I am sorry for the problem of limiting the number of recursive traversal times. First of all, I declare that the method I think is not good. if you think recursion is good, try to have such an array.

Array ([0] => Array ([id] => 49 [name] => Sports Department [parent_id] => 46 [children] => Array ([0] => Array ([id] => 52 [name] => Sports 1 Major [parent_id] => 49 [children] => Array ([0] => Array ([id] => 57 [name] => Class 1 [parent_id] => 52) [1] => Array ([id] => 58 [name] => Class 2 [parent_id] => 52) [2] => Array ([id] => 59 [name] => Study abroad class [parent_id] => 52 ))) [1] => Array ([id] => 53 [name] => Sports 2 Major [parent_id] => 49 [children] => Array ([0] => Array ([id] => 60 [name] => Class 1 [parent_id] => 53) [1] => Array ([id] => 61 [name] => Class 2 [parent_id] => 53) [2] => Array ([id] => 62 [name] => Class 3 [parent_id] => 53) [3] => Array ([id] => 63 [name] => Class 4 [parent_id] => 53) [4] => Array ([id] => 64 [name] => Class 5 [parent_id] => 53 ))))))

The specific array is like this.

Because the number of layers is not fixed, there may be children below. I want to set a number to limit the number of traversal layers. for example, to limit the number of traversal layers, the result is as follows:
It can be understood that a children program is a layer-1 program.

Array ([0] => Array ([id] => 49 [name] => Sports Department [parent_id] => 46 [children] => Array ([0] => Array ([id] => 52 [name] => Sports 1 Major [parent_id] => 49) [1] => Array ([id] => 53 [name] => Sports 2 Major [parent_id] => 49 ))))

Reply to discussion (solution)

Recursive pseudocode:

function getTortoise($arr, $flag){    if($flag===0) return;    foreach ($arr as $k => $v) {        //do something...        getTortoise($arr,$flag--);    }}

$ Ar = array (0 => array ('id' => '49', 'name' => 'Sports department ', 'parent _ id' => '46 ', 'Children '=> array (0 => array ('id' => '52', 'name' => 'Sports 1 professional ', 'parent _ id' => '49', 'Children '=> array (0 => array ('id' => '57 ', 'name' => 'class 1 ', 'parent _ id' => '52',), 1 => array ('id' => '58 ', 'name' => '2', 'parent _ id' => '52 ',), 2 => array ('id' => '59 ', 'name' => 'study abroad ', 'parent _ id' => '52 ',),),), 1 => array ('id' => '53', 'name' => 'Sports 2 professional', 'parent _ id' => '49 ', 'Children '=> array (0 => array ('id' => '60', 'name' => 'class 1 ', 'parent _ id' => '53',), 1 => array ('id' => '61 ', 'name' => '2 ', 'parent _ id' => '53',), 2 => array ('id' => '62', 'name' => '3ban ', 'parent _ id' => '53',), 3 => array ('id' => '63', 'name' => '4ban ', 'parent _ id' => '53',), 4 => array ('id' => '64', 'name' => '5ban ', 'parent _ id' => '53',); function foo ($ ar, $ deep =-1) {if ($ deep <0) return $ ar; $ res = array (); foreach ($ ar as $ k => $ r) {if (isset ($ r ['Children ']) {$ t = $ r ['Children']; unset ($ r ['Children ']); if ($ deep) $ r ['Children '] = foo ($ t, $ deep-1);} $ res [$ k] = $ r ;} return $ res;} print_r (foo ($ ar, 1 ));

Array ([0] => Array ([id] => 49 [name] => Sports Department [parent_id] => 46 [children] => Array ([0] => Array ([id] => 52 [name] => Sports 1 Major [parent_id] => 49) [1] => Array ([id] => 53 [name] => Sports 2 Major [parent_id] => 49 ))))

You can optimize it.

function foo($ar, $deep=-1) {  if($deep < 0) return $ar;  $res = array();  foreach($ar as $k=>$r) {    if(isset($r['children'])) {      if($deep) $r['children'] = foo($r['children'], $deep-1);      else unset($r['children']);    }    $res[$k] = $r;  }  return $res;}

The solution is perfect. thank you very much.