php递归实现无限级分类

1、递归组合多维数组

<?php
$a=array(
        0=>array('id'=>1,'title'=>'首页','pid'=>'0'),
        1=>array('id'=>2,'title'=>'技术','pid'=>'0'),
        2=>array('id'=>3,'title'=>'PHP','pid'=>'2'),
        3=>array('id'=>4,'title'=>'Linux','pid'=>'2'),
        4=>array('id'=>5,'title'=>'关于','pid'=>'0'),
);
function digui($arr,$sid=0){
	$res=array();
	foreach($arr as $k=>$v) {
		 if($v['pid']==$sid){
		 	$v['child']=digui($arr,$v['id']);
		 	$res[]=$v;
		 }
	}
    return $res;
}
print_r(digui($a));

2、递归组合一维数组

function digui2($arr,$html='--',$aid=0,$level=0){
	$result=array();
	foreach ($arr as $k => $v) {
		if($v['pid']==$aid){
			$v['level']=$level+1;
  			$v['html']=str_repeat($html,$level);
			$result[]=$v;
			$result=array_merge($result,digui2($arr,$html,$v['id'],$level+1));
		}
	}
	return $result;
}
print_r(digui2($a));