php – warning feof()期望参数1是资源

warning feof() expects parameter 1 to be resource

和

warning fread() expects parameter 1 to be resource

负责的代码是

<?php
    $file = '../upload/files/' . $filex;
    header("Content-Disposition: attachment; filename=" . urlencode($file));
    header("Content-Type: application/force-download");
    header("Content-Type: application/octet-stream");
    header("Content-Type: application/download");
    header("Content-Description: File Transfer");
    header("Content-Length: " . filesize($file));
    flush(); // this doesn't really matter.

    $fp = fopen($file,"r");
    while (!feof($fp)) {
        echo fread($fp,65536);
        flush(); // this is essential for large downloads
    }
    fclose($fp);
?>

我使用这个代码进行标题下载,但它现在吓坏了 – 在任何人询问我尝试过之前,我试过google但仍然不完全理解错误消息.