在php中下载多个文件作为zip而不保存在主机上

I use this way for download multiple files as zip :

$files = array('readme.txt', 'test.html', 'image.gif');
$zipname = 'file.zip';
$zip = new ZipArchive;
$zip->open($zipname, ZipArchive::CREATE);
foreach ($files as $file) {
  $zip->addFile($file);
}
$zip->close();

header('Content-Type: application/zip');
header('Content-disposition: attachment; filename='.$zipname);
header('Content-Length: ' . filesize($zipname));
readfile($zipname);

But the file file.zip be save on my host . I don't want to save on my host i just wanna download it withou save .

Thank