Send a limit recursive traversal of the problem for everyone to overcome, first of all, I think of the method is not good, I think the best recursive learning can try

There is such an array

Array ([0] = = Array ([id] = [name] = Sports Department [parent_id] + 46                            [Children] = = Array ([0] = = Array (                            [id] = [name] + Sports 1 professional [parent_id] = 49 [children] = = Array ([0]                                            = = Array ([id] = 57                                        [Name] = 1 class [parent_id] + 52                                            ) [1] = = Array (                               [ID] [[name] = + 2 class             [PARENT_ID] = [2] = Ar                                            Ray ([id] = 59                                        [Name] + Study Abroad class [parent_id] = 52                        ))) [1] = = Array                            ([id] = [name] + Sports 2 Professional                                    [PARENT_ID] = [children] = = Array (                                            [0] = = Array (                                            [ID] [Name] = 1 class   [parent_id] = 53                                     ) [1] = = Array ([id] = [name] + =                                    Class 2 [parent_id] = 53) [2] = = Array ([ ID] = [name] + 3 class [Parent                                        _ID] [3] = = Array                                            ([id] = 63                                        [Name] = 4 class [parent_id] + 53                       )             [4] = = Array ([id] =&gt ;  [Name] + 5 class [parent_id] =        53))) ))

The exact array is like this.

Because this layer is not fixed, there may be children, I would like to set a number, limit its traversal layer, such as limit traversal layer, the result is as follows:
Can be understood as a children is a layer, please master shot

Array (    [0] = = Array        (            [id] = [            name] = Sports Department            [PARENT_ID] + [            children] = Array                (                    [0] = =                        array                            ([id] = [                            name] = + Sport 1 Professional                            [parent_id]                    [1] = = Array                        (                            [id] = +                            [name] = + Sport 2 professional                            [parent_id]        ()))))

Reply to discussion (solution)

Recursive pseudo-code:

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

$ar = Array (0 = = Array (' id ' = ' + ', ' name ' = ' Sports Department ', ' parent_id ' = ' + '), ' children ' = Array (0 = = Array (' id ' = ' ' "'", ' name ' = ' = ' Sports 1 Professional ', ' parent_id ' = ' 49 ')  , ' children ' = = Array (0 = = Array (' id ' = ' + ', ' name ')             = ' 1 ', ' parent_id ' + ', ', ', ' 1 = = array (' id ' = ' 58 ',            ' Name ' = ' 2 ', ' parent_id ' + ', ', ' 2 = = Array (  ' id ' = ' (') ', ' name ' = + ' Study Abroad class ', ' parent_id ' + ' 52 ',), 1  = = Array (' id ' = ' + ', ' name ' = ' + ' Sports 2 professional ', ' parent_id ' + ', ' children '            = = Array (0 = = Array (' id ' = ' + ', ' name ' = ' 1 class '), ' parent_id ' = '",", "1" (' id ' = ' + ', ' name ' = ' 2 class ', ' parent_id ' = ' + ', ' 2 = = array (' id ' = ' + ', ' name ' = +            ' Class 3 ', ' parent_id ' = ' + ', ', ' 3 = = Array (' id ' = ' 63 ', ' Name ' = ' 4 ', ' parent_id ' = ' + ', ' 4 = = array (' ID ') = ' + ', ' name ' = ' 5 class ', ' parent_id ' = ' + ', '), '), '), ', '); func  tion foo ($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] = [            name] = Sports Department            [PARENT_ID] + [            children] = Array                (                    [0] = =                        array                            ([id] = [                            name] = + Sport 1 Professional                            [parent_id]                    [1] = = Array                        (                            [id] = +                            [name] = + Sport 2 professional                            [parent_id]        ()))))

Can optimize

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 was perfect, thank you very much.

