PHP recursively traverses multi-dimensional arrays to achieve infinite classification, recursive multi-dimensional_PHP tutorial

The method of PHP recursively traversing multi-dimensional arrays to achieve infinite classification, recursive multi-dimensional

The example in this article describes the method of PHP recursively traversing multi-dimensional arrays to achieve infinite classification. Share it with everyone for your reference, the details are as follows:

<&#63;php
   //$data[]=array('id'=>1,'parentid'=>0,'name'=>'中国','img'=>'52091199');
   $data[]=array('id'=>1,'parentid'=>0,'name'=>'中国');
   $data[]=array('id'=>2,'parentid'=>0,'name'=>'美国');
   $data[]=array('id'=>3,'parentid'=>0,'name'=>'韩国');
   $data[]=array('id'=>4,'parentid'=>1,'name'=>'北京');
   $data[]=array('id'=>5,'parentid'=>1,'name'=>'上海');
   $data[]=array('id'=>6,'parentid'=>1,'name'=>'广西');
   $data[]=array('id'=>7,'parentid'=>6,'name'=>'桂林');
   $data[]=array('id'=>8,'parentid'=>6,'name'=>'南宁');
   $data[]=array('id'=>9,'parentid'=>6,'name'=>'柳州');
   $data[]=array('id'=>10,'parentid'=>2,'name'=>'纽约');
   $data[]=array('id'=>11,'parentid'=>2,'name'=>'华盛顿');
   $data[]=array('id'=>12,'parentid'=>3,'name'=>'首尔');
   $tree=build_tree($data,0);
   //echo memory_get_usage();
   print_r($tree);
 function findChild(&$arr,$id){
  $childs=array();
  foreach ($arr as $k => $v){
   if($v['parentid']== $id){
    $childs[]=$v;
   }
  }
  return $childs;
 }
 function build_tree($rows,$root_id){
  $childs=findChild($rows,$root_id);
  if(empty($childs)){
   return null;
  }
 foreach ($childs as $k => $v){
  $rescurTree=build_tree($rows,$v['id']);
  if( null != $rescurTree){
  $childs[$k]['childs']=$rescurTree;
  }
 }
  return $childs;
 }
&#63;>

Run result:

Array
(
 [0] => Array
  (
   [id] => 1
   [parentid] => 0
   [name] => 中国
   [childs] => Array
    (
     [0] => Array
      (
       [id] => 4
       [parentid] => 1
       [name] => 北京
      )
     [1] => Array
      (
       [id] => 5
       [parentid] => 1
       [name] => 上海
      )
     [2] => Array
      (
       [id] => 6
       [parentid] => 1
       [name] => 广西
       [childs] => Array
        (
         [0] => Array
          (
           [id] => 7
           [parentid] => 6
           [name] => 桂林
          )
         [1] => Array
          (
           [id] => 8
           [parentid] => 6
           [name] => 南宁
          )
         [2] => Array
          (
           [id] => 9
           [parentid] => 6
           [name] => 柳州
          )
        )
      )
    )
  )
 [1] => Array
  (
   [id] => 2
   [parentid] => 0
   [name] => 美国
   [childs] => Array
    (
     [0] => Array
      (
       [id] => 10
       [parentid] => 2
       [name] => 纽约
      )
     [1] => Array
      (
       [id] => 11
       [parentid] => 2
       [name] => 华盛顿
      )
    )
  )
 [2] => Array
  (
   [id] => 3
   [parentid] => 0
   [name] => 韩国
   [childs] => Array
    (
     [0] => Array
      (
       [id] => 12
       [parentid] => 3
       [name] => 首尔
      )
    )
  )
)

Readers who are interested in more PHP-related content can check out the special topics on this site: "Complete PHP Array Operation Skills", "Summary of PHP Sorting Algorithms", "Summary of PHP Common Traversal Algorithms and Techniques", "PHP Data Structure and Algorithm Tutorial", "php Programming Algorithm Summary", "PHP Mathematical Operation Skills Summary", "php Regular Expression Usage Summary", "PHP Operations and Operator Usage Summary", "php String Usage Summary" 》and《Summary of common database operation skills in php》

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