PHP无限极分类函数的实现方法详解

function make_tree1($list,$pk='id',$pid='pid',$child='_child',$root=0){
  $tree=array();
  foreach($list as $key=> $val){
    if($val[$pid]==$root){
      //获取当前$pid所有子类
        unset($list[$key]);
        if(! empty($list)){
          $child=make_tree1($list,$pk,$pid,$child,$val[$pk]);
          if(!empty($child)){
            $val['_child']=$child;
          }
        }
        $tree[]=$val;
    }
  }
  return $tree;
}