Note that if you started called ob_start with a callback, that callback will still be called even if you discard the OB with ob_end_clean.
Because there is no way of removing the callback from the OB once you've set it, the only way to stop the callback function from having any effect is to do something like:
<?php
$ignore_callback = false;
ob_start('my_callback');
...
if($need_to_abort) {
$ignore_callback = true;
ob_end_clean();
...
}
function my_callback(&$buffer) {
if($GLOBALS['ignore_callback']) {
return "";
}
...
}
?>
ob_end_clean
(PHP 4, PHP 5, PHP 7, PHP 8)
ob_end_clean — Clean (erase) the contents of the active output buffer and turn it off
Descrizione
ob_end_clean(): bool
This function calls the output handler
(with the PHP_OUTPUT_HANDLER_CLEAN and
PHP_OUTPUT_HANDLER_FINAL flags),
discards it's return value,
discards the contents of the active output buffer
and turns off the active output buffer.
ob_end_clean() will fail
without an active output buffer started with the
PHP_OUTPUT_HANDLER_REMOVABLE flag.
ob_end_clean()
will discard the contents of the active output buffer
even if it was started without the
PHP_OUTPUT_HANDLER_CLEANABLE flag.
Elenco dei parametri
Questa funzione non contiene parametri.
Valori restituiti
Restituisce true in caso di successo, false in caso di fallimento.
Errori/Eccezioni
If the function fails it generates an E_NOTICE.
Esempi
The following example shows an easy way to get rid of the contents of the active output buffer:
Example #1 ob_end_clean() example
<?php
ob_start();
echo 'Text that won\'t get displayed.';
ob_end_clean();
?>Vedere anche:
- ob_start() - Turn on output buffering
- ob_get_contents() - Return the contents of the output buffer
- ob_clean() - Clean (erase) the contents of the active output buffer
- ob_get_clean() - Get the contents of the active output buffer and turn it off
- ob_end_flush() - Flush (send) the return value of the active output handler and turn the active output buffer off
add a note
User Contributed Notes 12 notes
John Smith ¶
20 years ago
Sam Yong - hellclanner at live dot com ¶
13 years ago
Take note that if you change zlib output compression setting in between ob_start and ob_end_clean or ob_end_flush, you will get an error: ob_end_flush() failed to delete buffer zlib output compression
Example:
<?php
ob_start();
$output = ob_get_contents();
ini_set('zlib.output_compression', '1');
ob_end_clean();
?>
ob_end_clean(); in this example will throw the error.
baklanoid at gmail dot com ¶
4 years ago
If there is no confidence about output buffering (enabled or not),
you may try these guards:
<?php
while (ob_get_level() !== 0) {
ob_end_clean();
}
// or
while (ob_get_length() !== false) {
ob_end_clean();
}
?>
programmer at bardware dot de ¶
21 years ago
You might want to prevent your script from executing if the client already has the latest version.
You can do it like so:
ob_start();
$mtime=filemtime($_SERVER["SCRIPT_FILENAME"])-date("Z");
$gmt_mtime = date('D, d M Y H:i:s', $mtime) . ' GMT';
$headers = getallheaders();
if(isset($headers["If-Modified-Since"])) {
if ($headers["If-Modified-Since"] == $gmt_mtime) {
header("HTTP/1.1 304 Not Modified");
ob_end_clean();
exit;
}
}
$size=ob_get_length();
header("Last-Modified: ".$gmt_mtime);
header("Content-Length: $size");
ob_end_flush();
Instead of checking the If-Modified-Since-Header against the date of the last modification of the script, you can of course query a database or take any other date that is somehow related to the modification of the result of your script.
You can for instance use this technique to generate images dynamically. If the user indicates he already has a version of the image by the If-Modified-Since-Header, there's no need to generate it and let the server finally discard it because the server only then interpretes the If-Modified-Since-Header.
This saves server load and shortens response-times.
everling ¶
18 years ago
Keep in mind that mrfritz379's example (#49800) is just an example. You can achieve that example's result in a more efficient manner without using output buffering functions:
echo "<p>Search running. Please be patient. . .";
$output = "<p>FileList: </p>\n";
if (is_dir($dir)) {
$dh = opendir($dir);
while (($fd = readdir($dh)) != false) {
echo " .";
$output .= $fd;
}
}
echo "</br>Search Complete!</p>\n";
echo $output;
In addition to John Smith's comment (#42939), ob_gzhandler() may still set the HTTP header "Content-Encoding" to "gzip" or "deflate" even if you call ob_end_clean(). This will cause a problem in the following situation:
1. Call ob_gzhandler().
2. Echo "Some content";
3. Call ob_end_clean().
4. Echo "New content";
In the above case, the browser may receive the "Content-Encoding: gzip" HTTP header and attempts to decompress the uncompressed "New content". The browser will fail.
In the following situation, this behaviour will go unnoticed:
1. Call ob_gzhandler().
2. Echo "Some content";
3. Call ob_end_clean().
4. Call ob_gzhandler().
5. Echo "New content";
This is because the second ob_gzhandler() will mask the absence of the first ob_gzhandler().
A solution would be to write a wrapper, like John Smith did, for the ob_gzhandler().
netom at elte dot hu ¶
14 years ago
Notice that ob_end_clean() does discard headers.
If you would like to clear the output buffer, but not the headers (because you use firephp for example...), than this is the solution:
<?php
...
$headers = array();
if ( !headers_sent() ) {
$headers = apache_response_headers();
}
ob_end_clean();
ob_start();
if ( !empty( $headers ) ) {
foreach ( $headers as $name => $value ) {
header( "$name: $value" );
}
}
...
?>
I use it in a general exception handler in a web application, where I clear the buffer (but not the debug-info-containing headers), and send a 500 error page with readfile().
Good PHPing,
Tamas.
daijoubuNOSP at Mvideotron dot com ¶
20 years ago
About the previous comment:
You can also relay on ETag and simply use time()
<?php
$time = time();
$mins = 1;
if (isset($_SERVER['HTTP_IF_NONE_MATCH']) and str_replace('"', '', $_SERVER['HTTP_IF_NONE_MATCH'])+($mins*60) > $time)
{
header('HTTP/1.1 304 Not Modified');
exit();
}
else
{
header('ETag: "'.$time.'"');
}
echo 'Caching for ', $mins*60, 'secs<br/>', date('G:i:s');
?>
geoff at spacevs dot com ¶
17 years ago
If you call ob_end_clean in a function registered with "register_shutdown_function", it is too late, any buffers will have already been sent out to the client.
Adam of Fusion Bay ¶
18 years ago
You may want to be careful about calling ob_end_clean() from within your call-back function. I believe this can produce an endless-loop within PHP.
mrfritz379 ¶
19 years ago
This may be posted elsewhere, but I haven't seen it.
To run a progress indicator while the program is running without outputting the output buffer, the following will work:
echo "<p>Search running. Please be patient. . .";
$output = "<p>FileList: </p>\n";
if (is_dir($dir)) {
$dh = opendir($dir);
while (($fd = readdir($dh)) != false) {
echo " .";
ob_start();
echo $fd;
$output .= ob_get_contents();
ob_end_clean();
}
}
echo "</br>Search Complete!</p>\n";
echo $output;
The program will continue to print the " ." without printing the file list. Then the "Search Complete" message will print followed by the buffered file list.
tyler @ ¶
16 years ago
In reference to <geoff at spacevs dot com> where he states, "If you call ob_end_clean in a function registered with 'register_shutdown_function', it is too late, any buffers will have already been sent out to the client.", here is a workaround I came up with.
<?php
function ClearBuffer($Buffer) {
return "";
}
function Shutdown() {
ob_start("ClearBuffer");
}
register_shutdown_function("Shutdown");
?>
This will wipe out all the contents of the output buffer as it comes in. Basically its the same as "STDOUT > /dev/null".
Anonymous ¶
7 years ago
To safely clear and close all non-lethal output buffers:
<?php
function ob_end_clean_all() {
$handlers = ob_list_handlers();
while (count($handlers) > 0 && $handlers[count($handlers) - 1] != 'ob_gzhandler' && $handlers[count($handlers) - 1] != 'zlib output compression') {
ob_end_clean();
$handlers = ob_list_handlers();
}
}
