找子孙树

$area = array(
    array(‘id‘=>1,‘name‘=>‘安徽‘,‘parent‘=>0),
    array(‘id‘=>2,‘name‘=>‘海淀‘,‘parent‘=>7),
    array(‘id‘=>3,‘name‘=>‘濉溪县‘,‘parent‘=>5),
    array(‘id‘=>4,‘name‘=>‘昌平‘,‘parent‘=>7),
    array(‘id‘=>5,‘name‘=>‘淮北‘,‘parent‘=>1),
    array(‘id‘=>6,‘name‘=>‘朝阳‘,‘parent‘=>7),
    array(‘id‘=>7,‘name‘=>‘北京‘,‘parent‘=>0),
    array(‘id‘=>8,‘name‘=>‘上地‘,‘parent‘=>2) );

// 找子孙树
// 用静态变量
/*
function subtree($arr,$id=0,$lev=1) {
    static $subs = array(); // 子孙数组
    foreach($arr as $v) {
        if($v[‘parent‘] == $id) {
            $v[‘lev‘] = $lev;
            $subs[] = $v; // 举例说找到array(‘id‘=>1,‘name‘=>‘安徽‘,‘parent‘=>0),
            subtree($arr,$v[‘id‘],$lev+1);
        }
    }
    return $subs;
}
// print_r(subtree($area,0,1));
*/
function subtree($arr,$id=0,$lev=1) {
    $subs = array(); // 子孙数组
    foreach($arr as $v) {
        if($v[‘parent‘] == $id) {
            $v[‘lev‘] = $lev;
            $subs[] = $v; // 举例说找到array(‘id‘=>1,‘name‘=>‘安徽‘,‘parent‘=>0),
            $subs = array_merge($subs,subtree($arr,$v[‘id‘],$lev+1));
        }
    }
    return $subs;
}
$tree = subtree($area,0,1);
foreach($tree as $v) {
    echo str_repeat(‘&nbsp;&nbsp;‘,$v[‘lev‘]),$v[‘name‘],‘<br />‘;
}