How do headers work with output buffering in PHP?

Question

Title is self-explanatory.

I have a good bit of experience with PHP, but I am not sure how the header function works between ob_start() and ob_end_clean().

Consider this:

ob_start();

echo "Some content";
header('X-Example-Header: foo');
echo "Some more content";

$output = ob_get_contents();
ob_end_clean();

echo $output;

Does the header function ignore the output buffering, and thus all headers get sent before the content because it is echoed after the header call?

Or does it work some other way?

(reference) ob_start — This function will turn output buffering on. While output buffering is active no output is sent from the script (other than headers), instead the output is stored in an internal buffer. — Gordon
– Gordon, Commented Jun 24, 2010 at 17:56
Oh, hey, I missed that. That should teach me to read a bit closer. Thanks, Gordon. — Austin Hyde
– Austin Hyde, Commented Jun 24, 2010 at 20:18

cletus · Accepted Answer · 2010-06-24 15:03:16Z

20

The header() does indeed ignore output buffering. Part of the reason to use output buffering is so you can send HTTP headers "out of order" since the response is buffered. You can't send HTTP headers once you've sent any kind of output (unless that output is buffered).

answered Jun 24, 2010 at 15:03

cletus

627k169 gold badges922 silver badges945 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

tim Over a year ago

Not really true github.com/php/php-src/issues/7953

Collectives™ on Stack Overflow

How do headers work with output buffering in PHP?

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related