树形展示分类

<?<br />$arr = array(<br />     <br />    array('id'=>1,'city_name'=>'中国','rel_id'=>'1','pid'=>0),<br />    array('id'=>2,'city_name'=>'广东','rel_id'=>'1-2','pid'=>1),<br />    array('id'=>3,'city_name'=>'深圳','rel_id'=>'1-2-3','pid'=>2),<br />    array('id'=>4,'city_name'=>'广州','rel_id'=>'1-2-4','pid'=>2)<br />    <br />);<br /> <br />function find_subclass( $pid ){<br />     <br />    global $arr;<br />    $__arr = array();<br />    foreach ( $arr as $k=>$v )<br />    {<br />         <br />        if( $v['pid']==$pid )$__arr[] = $v;<br />         <br />    }<br />    return $__arr;<br />     <br />}<br /> <br />function tree_subclass($pid=0){<br />     <br />    $__arr = array();<br />    $__arr = find_subclass($pid);<br />    if( !empty($__arr) ){<br />         <br />        foreach ( $__arr as $k=>$v )<br />        {<br /> <br />            $__arr[$k]['subclass'] = tree_subclass($v['id']);<br />             <br />        }<br />         <br />    }<br />    return $__arr;<br />}<br /> <br />var_dump(tree_subclass(0));<br /> <br />?>