PHP组指针赋值有关问题

$arr=array();
$arr['imagePath']="";
$arr['Size1']="";
$arr['imageaPath']="";
$arr['image2Path']="";
$arr['Size33']="";
$arr['image5Path']="";
$arr['Size55']="";
$arr['imagebbPath']="";
$arr['imageccPath']="";
$arr['Size555']="";
$arr['imageqqPath']="";
$arr['image99Path']="";
$arr['imageeePath']="";
$arr['imagepPath']="";
$arr['Size66']="";


$url='/';
$arr['imagePath']=$url;
$arr['imageaPath']=$url;
$arr['image2Path']=$url;
$arr['image5Path']=$url;
$arr['imagebbPath']=$url;
$arr['imageccPath']=$url;
$arr['imageqqPath']=$url;
$arr['image99Path']=$url;
$arr['imageeePath']=$url;
$arr['imagepPath']=$url;

foreach($ar as $k=?&$v) if(substr($k, -4) == 'Path') $v = $url;

$arr=array();
$arr['imagePath']="";
$arr['Size1']="";
$arr['imageaPath']="";
$arr['image2Path']="";
$arr['Size33']="";
$arr['image5Path']="";
$arr['Size55']="";
$arr['imagebbPath']="";
$arr['imageccPath']="";
$arr['Size555']="";
$arr['imageqqPath']="";
$arr['image99Path']="";
$arr['imageeePath']="";
$arr['imagepPath']="";
$arr['Size66']="";

$url = '/';

foreach($arr as $key=>$val){
    if(substr($key,0,5)=='image'){
        $arr[$key] = $url;
    }
}

print_r($arr);

?>