How to Force File Downloads with PHP Using `header()`?

Force File Download with PHP Using header()

1. The Problem:

You're attempting to enable users to download files from your server but the file is not prompting a "Save As" dialog.

2. The Cause:

Incorrect content type declaration in the header.

3. The Solution:

Ensure that the content type header is set to application/octet-stream for file downloads:

header('Content-Type: application/octet-stream');

4. Additional Tips:

• Use the addcslashes function to protect the filename from characters that may break the header.
• Set a specific filename for the downloaded file using Content-Disposition: attachment; filename= header.
• Specify the content length using the Content-Length header.
• Add headers to prevent caching and ensure the file is saved rather than displayed in the browser.

5. Example Code:

$quoted = sprintf('"%s"', addcslashes(basename($file), '"\'));
$size = filesize($file);

header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename=' . $quoted);
header('Content-Transfer-Encoding: binary');
header('Connection: Keep-Alive');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . $size);
readfile($file);

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