为什么我的PDF下载损坏了？

Question

I have a script that generates a pdf using fpdf, this file is saved correctly on the server on my computer. In that same php file I run the following code to download the file. When i download the pdf and I check it in notepad, everything in the pdf is the same, except for the fact that it contains a lot of my previous files html at the beginning of it. The file saved to my server doesn't have any of that.

What could cause something like this to happen? I have no idea where to look for the source of this error, can anyone point me in the direction to finding the problem?

<?php
$filename=($name.$ran.'.pdf');
$pdf->Output($name.$ran.'.pdf');

header ("Cache-Control: must-revalidate, post-check=0, pre-check=0");
    header('Content-Type: application/octetstream');
    header("Content-Transfer-Encoding: Binary");
    header("Content-length: ".filesize($filename));
    header("Content-disposition: attachment; filename=\"".basename($filename)."\"");
readfile($name.$ran.'.pdf');
?>

Answer 1

I managed to figure things out, thanks to hakre! Essentially I just needed to clear out the output buffer using ob_clean () before using readfile() and the code worked!