How to return a file in PHP

I have a file

/file.zip

A user comes to

/download.php

I want the user’s browser to start downloading the file. How do i do that? Does readfile open the file on server, which seems like an unnecessary thing to do. Is there a way to return the file without opening it on the server?

Answer

I think you want this:

        $attachment_location = $_SERVER["DOCUMENT_ROOT"] . "/file.zip";
        if (file_exists($attachment_location)) {

            header($_SERVER["SERVER_PROTOCOL"] . " 200 OK");
            header("Cache-Control: public"); // needed for internet explorer
            header("Content-Type: application/zip");
            header("Content-Transfer-Encoding: Binary");
            header("Content-Length:".filesize($attachment_location));
            header("Content-Disposition: attachment; filename=file.zip");
            readfile($attachment_location);
            die();        
        } else {
            die("Error: File not found.");
        }