How Can I Force File Downloads in PHP Using `header()` and Avoid Browser Display Issues?

Force File Download with PHP Using Header()

Issue:
Despite various attempts, users experience difficulties in prompting file downloads from a server using PHP's header() function. They observe the necessary headers being sent but encounter issues with displaying the save dialog.

Solution:
To successfully force file downloads, the headers must be set appropriately. The following code addresses the concerns raised:

$quoted = sprintf('"%s"', addcslashes(basename($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);

Key Differences from Previous Attempts:

1. Content-Type: The correct content type for file downloads is "application/octet-stream" instead of "image/png."
2. Filename Quoting: The filename must be properly quoted to prevent potential malicious characters from being interpreted.
3. Additional Headers: The code includes "Connection: Keep-Alive" and "Expires: 0" headers, which help ensure reliable connections and prevent caching issues.

Verified Browsers:
This solution has been confirmed to work in Firefox 8.0.1, Chrome 15.0.874.121, and Safari 5.1.1.

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