Recipe 8.13 Buffering Output to the Browser
8.13.1 Problem
You want to start generating
output before you're finished sending headers or
cookies.
8.13.2 Solution
Call ob_start( ) at the top of your page and
ob_end_flush( ) at the bottom. You can then intermix commands
that generate output and commands that send headers. The output
won't be sent until ob_end_flush(
) is called:
<?php ob_start(); ?>
I haven't decided if I want to send a cookie yet.
<?php setcookie('heron','great blue'); ?>
Yes, sending that cookie was the right decision.
<?php ob_end_flush(); ?>
8.13.3 Discussion
You can pass ob_start( ) the name of a callback
function to process the output buffer with
that function. This is useful for postprocessing all the content in a
page, such as hiding email addresses from address-harvesting
robots:
<?php
function mangle_email($s) {
return preg_replace('/([^@\s]+)@([-a-z0-9]+\.)+[a-z]{2,}/is',
'<$1@...>',
$s);
}
ob_start('mangle_email');
?>
I would not like spam sent to ronald@example.com!
<?php ob_end_flush(); ?>
The mangle_email(
)
function transforms the output to:
I would not like spam sent to <ronald@...>!
The
output_buffering configuration directive
turns output buffering on for all pages:
output_buffering = On
Similarly,
output_handler sets an output buffer
processing callback to be used on all pages:
output_handler=mangle_email
Setting an output_handler automatically sets
output_buffering to on.
8.13.4 See Also
Recipe 10.11 uses output buffering in a
database error logging function; documentation on ob_start(
) at http://www.php.net/ob-start,
ob_end_flush( ) at
http://www.php.net/ob-end-flush, and output
buffering at http://www.php.net/outcontrol.
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