php两种无限分类方法实例

一、递归方法
复制代码代码如下:
$items = array（
array（"id"=>1,"pid"=>0,"name"=>"一级11"）,
array（"id"=>2,"pid"=>0,"name"=>"一级12"）,
array（"id"=>3,"pid"=>1,"name"=>"二级21"）,
array（"id"=>4,"pid"=>3,"name"=>"三级31"）,
array（"id"=>5,"pid"=>1,"name"=>"二级22"）,
array（"id"=>6,"pid"=>3,"name"=>"三级32"）,
array（"id"=>7,"pid"=>6,"name"=>"四级41"）,
）;
$i = 0;
function formatTree（$arr, $pid = 0）{
$tree = array（）;
$temp = array（）;
global $i;
if（$arr）{
foreach（$arr as $k=>$v）{
if（$v["pid"] == $pid）{//
$temp = formatTree（$arr, $v["id"]）;
$temp && $v["son"] = $temp;
$tree[] = $v;
}
}
}
return $tree;
}
print_r（formatTree（$items））;

二、非递归方法
复制代码代码如下:
function genTree（$items） {
    $tree = array（）; //格式化好的树
    foreach （$items as $item）
        if （isset（$items[$item["pid"]]））{
            $items[$item["pid"]]["son"][] = &$items[$item["id"]];
        }
        else{
            $tree[] = &$items[$item["id"]];
        }
    return $tree;
}
$items = array（
    1 => array（"id" => 1, "pid" => 0, "name" => "一级11"）,
    2 => array（"id" => 2, "pid" => 1, "name" => "二级21"）,
    3 => array（"id" => 3, "pid" => 1, "name" => "二级23"）,
    4 => array（"id" => 4, "pid" => 9, "name" => "三级31"）,
    5 => array（"id" => 5, "pid" => 4, "name" => "四级43"）,
    6 => array（"id" => 6, "pid" => 9, "name" => "三级32"）,
    7 => array（"id" => 7, "pid" => 4, "name" => "四级41"）,
    8 => array（"id" => 8, "pid" => 4, "name" => "四级42"）,
    9 => array（"id" => 9, "pid" => 1, "name" => "二级25"）,
    10 => array（"id" => 10, "pid" => 11, "name" => "二级22"）,
    11 => array（"id" => 11, "pid" => 0, "name" => "一级12"）,
    12 => array（"id" => 12, "pid" => 11, "name" => "二级24"）,
    13 => array（"id" => 13, "pid" => 4, "name" => "四级44"）,
    14 => array（"id" => 14, "pid" => 1, "name" => "二级26"）,
    15 => array（"id" => 15, "pid" => 8, "name" => "五级51"）,
    16 => array（"id" => 16, "pid" => 8, "name" => "五级52"）,
    17 => array（"id" => 17, "pid" => 8, "name" => "五级53"）,
    18 => array（"id" => 18, "pid" => 16, "name" => "六级64"）,
）;
print_r（genTree（$items））;