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PHP : Function Reference : Output Control Functions : ob_start

ob_start

Turn on output buffering (PHP 4, PHP 5)
bool ob_start ( [callback output_callback [, int chunk_size [, bool erase]]] )

Example 1691. User defined callback function example

copy to clipboard
<?php

function callback($buffer)
{
 // replace all the apples with oranges
 return (str_replace("apples", "oranges", $buffer));
}

ob_start("callback");

?>
<html>
<body>
<p>It's like comparing apples to oranges.</p>
</body>
</html>
<?php

ob_end_flush();

?>

The above example will output:

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<html>
<body>
<p>It's like comparing oranges to oranges.</p>
</body>
</html>

Related Examples ( Source code ) » ob_start

Examples ( Source code ) » Arrays Using Associative Array Notation
Examples ( Source code ) » Handling OCI8 Errors

Code Examples / Notes » ob_start

ray paseur paseur ... imaginedb.com
You can use PHP to generate a static HTML page.  Useful if you have a complex script that, for performance reasons, you do not want site visitors to run repeatedly on demand.  A "cron" job can execute the PHP script to create the HTML page.  For example:
<?php // CREATE index.html
  ob_start();
/* PERFORM COMLEX QUERY, ECHO RESULTS, ETC. */
  $page = ob_get_contents();
  ob_end_clean();
  $cwd = getcwd();
  $file = "$cwd" .'/'. "index.html";
  @chmod($file,0755);
  $fw = fopen($file, "w");
  fputs($fw,$page, strlen($page));
  fclose($fw);
  die();
?>

ernest
When you rely on URL rewriting to pass the PHP session ID you should be careful with ob_get_contents(), as this might disable URL rewriting completely.
Example:
ob_start();
session_start();
echo '<a href=".">self link</a>';
$data = ob_get_contents();
ob_end_clean();
echo $data;
In the example above, URL rewriting will never occur. In fact, rewriting would occur if you ended the buffering envelope using ob_end_flush(). It seems to me that rewriting occurs in the very same buffering envelope where the session gets started, not at the final output stage.
If you need a scenario like the one above, using an "inner envelope" will help:
ob_start();
ob_start();   // add the inner buffering envelope
session_start();
echo '<a href=".">self link</a>';
ob_end_flush(); // closing the inner envelope will activate URL rewriting
$data = ob_get_contents();
ob_end_clean();
echo $data;
In case you're interested or believe like me that this is rather a design flaw instead of a feature, please visit bug #35933 (http://bugs.php.net/bug.php?id=35933) and comment on it.

geoffrey
When using a callback with ob_start(), functions like ob_get_contents() don't make use of it, use ob_end_flush() instead.
nb: not tested with every ob_* functions, just ob_get_contents() and ob_end_flush()

asher haig ahaig
When a script ends, all buffered output is flushed (this is not a bug: http://bugs.php.net/bug.php?id=42334&thanks=4). What happens when the script throws an error (and thus ends) in the middle of an output buffer? The script spits out everything in the buffer before printing the error!
Here is the simplest solution I have been able to find. Put it at the beginning of the error handling function to clear all buffered data and print only the error:
$handlers = ob_list_handlers();
while ( ! empty($handlers) ) {
ob_end_clean();
$handlers = ob_list_handlers();
}

tracey
Way to make all stdout and stderr write to a log
from *inside* a php script.
You simply need to make sure to call elog() every
once in awhile to get output.
It's a nice way to "daemonize" a script w.r.t. its logging.
// This allows us to capture all stdout and stderr (and error_log() calls)
// to this logfile...
// The "collected output" will be flushed anytime "elog()" is used...
ini_set("error_log", "/var/log/script.log");
ob_start();
function elog($str)
{
 // get anything written to stdout or stderr that did *NOT* use elog()
 // and write it now...
 $writeme = ob_get_contents();
 if ($writeme)
 {
   error_log($writeme);
   ob_end_clean();
   ob_start();
 }
 // now write message this method was called with
 error_log($str);
}

charlie farrow
Under certain freak conditions, when an error ocours perfoming an action on an object that cannot be done (either because the object does not exist or the method does not exist) inside of an ob_start() the script will exit and print everything the current function generates before the error, but nothing else, including no error message.
I am at a loss to why no error message appears and am trying to get a working example for the developers that is simpler than my whole program!
So if you are using ob_start() and you get no output, check your objects.... you have made a mistake on them somewhere. The only trouble is you will not know where as there is no error!!

denis
This function's behaviour  has been changed in php 5.2.0:
<?
global $AP;
$AP = new ap;
ob_start("ob_end");
function ob_end() {
       global $AP;
       $r = $AP->test();
       return $r;
}
class ap {
       function test() {
               return "debug";
       }
}
?>
In older versions it shows: "debug".
But latest php version causes error: PHP Fatal error: Call to a member function test() on a non-object.
And this is not a bug: http://bugs.php.net/bug.php?id=40104

aleksey
This function dynamically changes title of HTML page:
 function change_title($new_title) {
   $output = ob_get_contents();
   ob_end_clean();
   $output = preg_replace("/<title>(.*?)<\/title>/", "<title>$new_title</title>", $output);
   echo $output;
 }
Example:
 ob_start();
 // ... some output
 change_title('NEW TITLE!');

jds1509
This code demonstrates the affect of providing a value to the chunk_size parameter. A value of 1 or 0 will be ignored by php. Here's the Code:
<?
function callback($buffer)
{
return "TRAPPED:".$buffer."<br/>";
}
ob_start("callback",2);
echo "long string, so callback";
echo "X";
echo " - no callback, less than 2 chars";
?>newlines,
but
no
callback
!<?
// PHP block
?>PHP block initiates callback.<?
echo "One more callback at EOF...";
?>
The code above outputs:
TRAPPED:long string, so callback
TRAPPED:X - no callback, less than 2 chars
TRAPPED:newlines, but no callback !
TRAPPED:PHP block initiates callback.
TRAPPED:One more callback at EOF...
TRAPPED:

oersoep
These are handy. First one has been mentioned before.
ob_start( array( 'lib_class', 'parse_output' ) );
ob_start( array( $this, 'parse_output' ) );
Note: $this is NOT a reference. Anything the callback saves or logs disappears in the clone ob_start works with.
It does enable the callback to work with the attributes of $this, like $this->ar_tpl_value or whatever your style is.
The manual says:
"If the optional parameter chunk_size is passed, the callback function is called on every first newline after chunk_size bytes of output. The output_callback parameter may be bypassed by passing a NULL value."
This doesn't work with my 4.3.11. Might be the Zend optimizer though. Daren't turn it off to go see.

php
The following should be added: "If outbut buffering is still active when the script ends, PHP outputs it automatically. In effect, every script ends with ob_end_flush()."

butch
simple code to make phpsession $_GET nice for Valid XHTML 1.0 Transitional :)
function callback($buffer)
{
 $buffer = str_replace("&PHPSESSID", "&amp;PHPSESSID", $buffer);
 return $buffer;
}
ob_start("callback");
session_start();

feedback
PHP Suggests: Some web servers (e.g. Apache) change the working directory of a script when calling the callback function. You can change it back by doing, for example, the following in the callback function: chdir(dirname($_SERVER['SCRIPT_FILENAME']))
The solution provided by PHP, does not function as intended when running PHP as a CGI (on CGI mode (CGI-BUILD (--enable-cgi) and/or CLI)).  In such a case, PHP is executed as a CGI-BIN and the web server daemon (e.g. Apache) sees SCRIPT_FILENAME as being the PHPCGI processor, and won't look deeper to find what file the PHPCGI processor is actually running/parsing; therefore the path returned by SCRIPT_FILENAME is wrong (most of the time, containing/ending with "cgi-system/php.cgi").
As SCRIPT_FILENAME is the safest way to proceed, but turns to be wrong in this exact situation; PATH_TRANSLATED is the next safe solution one would turn towards since it is populated with a different mechanism.
It would be correct to develop in the direction if the script filename itself is contained in the SCRIPT_FILENAME path value, then the SCRIPT_FILENAME content is reported correctly. If it is not, using PATH_TRANSLATED is the next logical choice we can use. The best reference in this case would be PHP_SELF as it is populated by PHP itself. Using SCRIPT_NAME as a reference would be an error as it is affected by the same problem (reports cgi-system and/or php.cgi as well).
The following is the revised code and should work on both the non-CGI and the CGI PHP processor types.
<?php
chdir(dirname((strstr($_SERVER["SCRIPT_FILENAME"], $_SERVER["PHP_SELF"])
? $_SERVER["SCRIPT_FILENAME"] : $_SERVER["PATH_TRANSLATED"])));
?>
Or the decomposed code as follows:
<?php
if (strstr($_SERVER["SCRIPT_FILENAME"], $_SERVER["PHP_SELF"])) {
$reference = $_SERVER["SCRIPT_FILENAME"];
} else {
$reference = $_SERVER["PATH_TRANSLATED"];
}
chdir(dirname($reference);
?>
This has been tested on Apache 1 & 2, PHP 4 & 5 and IIS 5.1

ed.oohay a suamhcs_rodnan
Output Buffering even works in nested scopes or might be applied in recursive structures... thought this might save someone a little time guessing and testing :)
<pre><?php
   
   ob_start();              // start output buffer 1
   echo "a";                // fill ob1
       
       ob_start();              // start output buffer 2
       echo "b";                // fill ob2
       $s1 = ob_get_contents(); // read ob2 ("b")
       ob_end_flush();          // flush ob2 to ob1
       
   echo "c";                // continue filling ob1
   $s2 = ob_get_contents(); // read ob1 ("a" . "b" . "c")
   ob_end_flush();          // flush ob1 to browser
   
   // echoes "b" followed by "abc", as supposed to:
   echo "<HR>$s1<HR>$s2<HR>";
   
?></pre>
... at least works on Apache 1.3.28
Nandor =)

capitals the mayor and those@gmail
One of the notes below mentions that ob_end_flush() is called automatically at the end of the script if you called ob_start without an ob_end.
Because I couldn't find any other way to do it, I tried to use this fact to have some stuff run at the end of every script. It was a maintenance nightmare, so I'm putting a link here to the good way to do it, since it's nigh impossible to find with google.
http://php.net/register_shutdown_function

clement dot ayme
ob_start() seems not compliant with command-line PHP.
just calling the function ahead of your unix-php script and nothing
happens. The STDOUT stream is not buffered.

zeisss
Note that the current working directory changes in the callback procedure (Changed from htdocs\ to windows\system32\ on my system).
You have to use absolut paths if you want to open files on your local system.

d_spagnoli
nl2br() is not a callable function, to make it work define a new one like this:
function mynl2br($str){
return nl2br($str);
}
example:
ob_start("nl2br");
echo "under pressure\npushing down on me";
$str_error=ob_get_flush();
doesn't work, use ob_start("mynl2br") instead.
PHP 4.3.9

aaron
My callback is stored in a function class, and using ob_start ('Class::callback') wasn't working. Not wanting to instantiate the class (no need, it's a function class) I tried this and it worked a charm:
ob_start (array (Class, 'callback'));
PHP 4.3.4

lucky760
Just for simplicity's sake (and because I had to rewrite it for use at http://www.VideoSift.com anyway), here's a very simplified, pre-PHP5 version. Just add one call to dump_css_cache() for each of your CSS files.
<?php
ob_start('ob_gzhandler');
header('Content-Type: text/css; charset: UTF-8');
header('Cache-Control: must-revalidate');
$expire_offset = 0; // set to a reaonable interval, say 3600 (1 hr)
header('Expires: ' . gmdate('D, d M Y H:i:s', time() + $expire_offset) . ' GMT');
function css_compress($buffer) {
 $buffer = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $buffer);// remove comments
 $buffer = str_replace(array("\r\n", "\r", "\n", "\t", '  '), '', $buffer);// remove tabs, spaces, newlines, etc.
 $buffer = str_replace('{ ', '{', $buffer);// remove unnecessary spaces.
 $buffer = str_replace(' }', '}', $buffer);
 $buffer = str_replace('; ', ';', $buffer);
 $buffer = str_replace(', ', ',', $buffer);
 $buffer = str_replace(' {', '{', $buffer);
 $buffer = str_replace('} ', '}', $buffer);
 $buffer = str_replace(': ', ':', $buffer);
 $buffer = str_replace(' ,', ',', $buffer);
 $buffer = str_replace(' ;', ';', $buffer);
 return $buffer;
}
function dump_css_cache($filename) {
 $cwd = getcwd() . DIRECTORY_SEPARATOR;
 $stat = stat($filename);
 $current_cache = $cwd . '.' . $filename . '.' . $stat['size'] . '-' . $stat['mtime'] . '.cache';
 // the cache exists - just dump it
 if (is_file($current_cache)) {
   include($current_cache);
   return;
 }
 // remove any old, lingering caches for this file
 if ($dead_files = glob($cwd . '.' . $filename . '.*.cache', GLOB_NOESCAPE))
   foreach ($dead_files as $dead_file)
     unlink($dead_file);
 
 if (!function_exists('file_put_contents')) {
   function file_put_contents($filename, $contents) {
     $handle = fopen($filename, 'w');
     fwrite($handle, $contents);
     fclose($handle);
   }
 }
 
 $cache_contents = css_compress(file_get_contents($filename));
 file_put_contents($current_cache, $cache_contents);
 
 echo $cache_contents;
}
dump_css_cache('_general.css');
?>

mjr
If you're using object-orientated code in PHP you may, like me, want to use a call-back function that is inside an object (i.e. a class function). In this case you send ob_start a two-element array as its single argument. The first element is the name of the object (without the $ at the start), and the second is the function to call. So to use a function 'indent' in an object called '$template' you would use <?php ob_start(array('template', 'indent')); ?>.

05-dec-2002 08:02
If you're using Apache (1.3x or 2.0), you might consider adding automatic compression capability to your delivered pages.
I assume you all know how to build compression classes and use them in your programs, but none has yet to offer the speed and robustness of a binary-compiled module. Furthermore, such modules also log the "compressable" hit in the web log file, thus allowing your favorite web anaysing program to show you reports of bandwidth saved.
Having said that, you might consider the following two modules for Apache:
1) Apache 1.3x: use mod_gzip, available from:
http://sourceforge.net/projects/mod-gzip/
2) Apache 2.x: use mod_gz, see here:
http://www.mail-archive.com/dev@httpd.apache.org/msg00734.html
3) Apache 1.3x: you may also want to use mod_defalte, from:
ftp://ftp.lexa.ru/pub/apache-rus/contrib/
Hope it helps.

cyrille.berliat no spam free.fr
If you're trying to use ob_start() in some PHP5 classes (probably works on PHP4 classes), this is the good way :
<?
class HTMLPage
{
//----------------------------------------------------------------- PUBLIC
//----------------------------------------------------- Méthodes publiques
   
   public static function ConvertIntoSGML( $source )
   // Mode d'emploi :
   //convertit une string en une SGML valide
   //
   // Renvoie :
   //la chaine traitée
   //
   // Algorithme :
   //analyse char par char de la chaine. Si un caractère est de nombre ASCII > 127,
   //conversion en son code SGML.
   {
       $newString = '';
       
       for( $i = 0; $i < strlen( $source ) ; $i++ ) {
           $o = ord( $source{ $i } );
           
           $newString .= ( ( $o > 127 ) ? '&#'.$o.';': $source{ $i } );
       }
       
       return $newString;
   }
   
   public function FlushSite( $source )
   {
       return $this->ConvertIntoSGML ( $source );
   }
   
//-------------------------------------------- Constructeurs - destructeur
   function __construct()
   // Mode d'emploi (constructeur) :
   //initialise la buffurisation
   //
   // Contrat :
   //
   {
ob_start( array (  & $this , 'FlushSite' ) );
   } //---- Fin du constructeur
   
//------------------------------------------------------ Méthodes Magiques
//------------------------------------------------------------------ PRIVE
}
// Example :
$webdesign = new HTMLPage ( );
echo 'Héllo world'; // Will produce the source 'h&#233;llo world'
?>
Without the & before $this, you'll loose your content because ob_start() will call the flushsite() function from a clone of the object and not the caller object himself.
Note : call_back function must be public because ob_start() is in an extern scope from your class :)
I hope this will help you!

rafa dot chacon
If you're trying to include a php file inside a loop by require_once (in example, a dinamic email template) and change the value of some variables (in example, url to unsuscribe, different for each user), you should use
<?php
// ... some code
$usermail = array("email1", "email2", ...);
for($i = 0; $i < $MAX; $i++)
{
       $usermail_unsuscribe = $usermail[$i];
       ob_start();
       include("email_template.php");
       ob_clean();
}
?>
Otherwise $usermail_unsuscribe will get only "email1" value.

admin
If you want to run code in the middle of a string that you made, but you want to wait the printing...
(so if you want to allow php in bb-code style, and you want to execute it in order, and print everything in order...)
phpRun($code) {
   ob_start();
   exec($code);
   $output = ob_get_contents();
   ob_end_clean();
   return $output;
}
$str = str_replace("]\n", "]", $str);
$match = array('#\[php\](.*?)\[\/php\]#se');
$replace = array( phpRun( stripslashes('$1') ) );
$str= preg_replace($match, $replace, $str);
echo $str;

jkloss
If ob_start does not seem to be working for you, note that with Apache 2 the flush() function causes PHP to send headers regardless of whether ob_start had been called before flush.
ob_start();
echo 'test';
flush();
will cause Apache 2 to send whatever headers may be stacked up - which means you can't use a header(location:xxx) after the flush.  To fix, remove the flush().  Spent several hours discovering this.  Apache 1.x didn't work this way.

venky_athome
IE 55. sp2 and IE6 as on the date of adding this note have problems with content type gzip and caching http headers. The pages are never cached. I think this combination of http headers can also crash the browser.
see http://support.microsoft.com/default.aspx?scid=kb;en-us;321722

fb
I've noticed a bug with MSIE for non cached contents if your page is less than 4096 octets : you have to refresh the page each time to view its content !
Here is the solution to prevent this stupid behaviour of MSIE : just insert this code at the top of your scripts :
function ob_callback($buffer)
{
return $buffer . str_repeat(' ', max(0, 4097 - strlen($buffer)));
}
ob_start('ob_callback');

10-nov-2006 06:34
I'm sure some of you more brilliant minds could pare this down some more, but using the method found at fiftyfoureleven.com  for compressing, I got my 10090-byte stylesheet down to 3536 bytes and then again down to 2713 bytes, by stripping unecessary characters from the stylesheet. 2 ob_start calls and the CSS file is now 73% smaller. YMMV.
<?php
ob_start("ob_gzhandler");
ob_start("compress");
header("Content-type: text/css; charset: UTF-8");
header("Cache-Control: must-revalidate");
$off = 0; # Set to a reaonable value later, say 3600 (1 hr);
$exp = "Expires: " . gmdate("D, d M Y H:i:s", time() + $off) . " GMT";
header($exp);
function compress($buffer) {
$buffer = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $buffer); // remove comments
$buffer = str_replace(array("\r\n", "\r", "\n", "\t", '  ', '    ', '    '), '', $buffer); // remove tabs, spaces, newlines, etc.
$buffer = str_replace('{ ', '{', $buffer); // remove unnecessary spaces.
$buffer = str_replace(' }', '}', $buffer);
$buffer = str_replace('; ', ';', $buffer);
$buffer = str_replace(', ', ',', $buffer);
$buffer = str_replace(' {', '{', $buffer);
$buffer = str_replace('} ', '}', $buffer);
$buffer = str_replace(': ', ':', $buffer);
$buffer = str_replace(' ,', ',', $buffer);
$buffer = str_replace(' ;', ';', $buffer);
return $buffer;
}
require_once('screen.css');
require_once('layout.css');
require_once('custom.php');
require_once('titles.css');
require_once('bus.css');
?>

dev
I wanted to do things a very particular way with output buffering and shutdown functions; using register_shutdown_function instead of the built in callback feature of this function. However, one should note that this won't work, because the contents of the buffer are no longer in scope when PHP is calling the shutdown functions. This would have been easy to see EXCEPT that PHP graciously flushes any unsent buffers at the end of the script, or when calling exit. So:
<?php
   ob_start();
   echo 'hi';
   exit;
?>
Prints "hi". In a nutshell, if you want it to have a shutdown function that handles an output buffer, just specify it in ob_start() and let PHP automatically call it at the end of the script.

05-aug-2005 03:54
I usually create my pages in four parts - variable initialisation, import header (using the variables just declared to configure), main body (mostly non-PHP), import footer.  I wondered about making the main body examinable by another PHP script if the main page was included into it.  I found I could control output of the main body by ending the header with an unclosed function which finishes at the start of the footer, thus enclosing the main body.  Output buffering can then be used to read this into a variable.  As a demonstration of how this can be used to control the order of output look at this example:
<?php
$output = "";
// Callback to process buffered output
function capture($buffer)
{
$GLOBALS['output'] .= $buffer;
return "C ";
}
// Calls the printE() function with output capture
function captureE()
{
ob_start("capture");
printE();
ob_end_flush();
}
?>
A
<?php
// Output 'E' (the main body in the example scenario)
function printE()
{ // (End header after this line) ?>
E
<?php // (Start footer with this line)
}
?>
B
<?php captureE(); ?>
D
<?php print $output; ?>
F
<?php printE(); ?>
G
The output is A B C D E F E G.
For the application I mentioned above there are two points to note:
- The page when executed alone must output its main body but the inspection script should suppress this, perhaps by means of a variable set before the page is included and then checked for in the footer output lines.
- Because the main body is now inside a function it has a different namespace, thus changes may be required to prevent code breaking (e.g. use of globals, handling of functions defined within the main body).

tobias goldkamp
I use this to strip unnecessary characters from HTML output:
<?php
function sanitize_output($buffer)
{
$search = array(
'/\>[^\S ]+/s', //strip whitespaces after tags, except space
'/[^\S ]+\</s', //strip whitespaces before tags, except space
'/(\s)+/s'  // shorten multiple whitespace sequences
);
$replace = array(
'>',
'<',
'\\1'
);
 $buffer = preg_replace($search, $replace, $buffer);
return $buffer;
}
ob_start("sanitize_output");
?>

eddie
I use this function for deleting not needed characters within the html code before sending the whole stuff to the browser.
function callback($buffer){
$buffer = str_replace("\n", "", $buffer);
$buffer = str_replace("\t", "", $buffer);
$buffer = str_replace(chr(13), "", $buffer);
$buffer = ereg_replace("<!\-\- [\/\ a-zA-Z]* \-\->", "", $buffer);
return $buffer;
}
First str_replace will delete any newlines, second any tabs and the third any carriage return. Finally the regular expression will delete any html-comment which consists of /, space, a-z or A-Z.
Using this saves about 1kb on every pageload.

jm
I don't claim to understand this--I would have expected the exact opposite--but it seems that
 ob_start() ... ob_end_flush()
can massively improve perfomance, by at least a factor of 10 (admittedly a small number of samples).
I tried this after discovering that I could move a large (100ms) bottleneck in one of my scripts into
  echo "<!-- about 40 characters of junk -->";
which clearly shouldn't have taken long to run.
My unfounded theory is that without buffering, the interaction between PHP4.3.4 and Apache is not optimized, whereas with buffering, PHP delivers the entire page at once, which Apache handles better.
I should add that this is under https.

joebezucha
Hi, I use those functions for stripping unnecessary chars in my output code...because I have JavaScript placed in outpout code so I don't remove \n\r\t but just replace them with single space (it could cause errors in scripts)
Function stripBufferSkipTextareaTags skips tags Textarea. It's needed to don't loose \n\r when user edit some content...
sorry for my english ;)
<?php
function stripBufferSkipTextareaTags($buffer){
$poz_current = 0;
$poz_end = strlen($buffer)-1;
$result = "";

while ($poz_current < $poz_end){
$t_poz_start = stripos($buffer, "<textarea", $poz_current);
if ($t_poz_start === false){
$buffer_part_2strip = substr($buffer, $poz_current);
$temp = stripBuffer($buffer_part_2strip);
$result .= $temp;
$poz_current = $poz_end;
}
else{
$buffer_part_2strip = substr($buffer, $poz_current, $t_poz_start-$poz_current);
$temp = stripBuffer($buffer_part_2strip);
$result .= $temp;
$t_poz_end = stripos($buffer, "</textarea>", $t_poz_start);
$temp = substr($buffer, $t_poz_start, $t_poz_end-$t_poz_start);
$result .= $temp;
$poz_current = $t_poz_end;
}
}
return $result;
}
function stripBuffer($buffer){
// change new lines and tabs to single spaces
$buffer = str_replace(array("\r\n", "\r", "\n", "\t"), ' ', $buffer);
// multispaces to single...
$buffer = ereg_replace(" {2,}", ' ',$buffer);
// remove single spaces between tags
$buffer = str_replace("> <", "><", $buffer);
// remove single spaces around &nbsp;
$buffer = str_replace(" &nbsp;", "&nbsp;", $buffer);
$buffer = str_replace("&nbsp; ", "&nbsp;", $buffer);
return $buffer;
}
ob_start("stripBufferSkipTextareaTags");
?>

net_navard
Hello firends
ob_start() opens a buffer in which all output is stored. So every time you do an echo, the output of that is added to the buffer. When the script finishes running, or you call ob_flush(), that stored output is sent to the browser (and gzipped first if you use ob_gzhandler, which means it downloads faster).
The most common reason to use ob_start is as a way to collect data that would otherwise be sent to the browser.
These are two usages of ob_start():
1-Well, you have more control over the output. Trivial example: say you want to show the user an error message, but the script has already sent some HTML to the browser. It'll look ugly, with a half-rendered page and then an error message. Using the output buffering functions, you can simply delete the buffer and sebuffer and send only the error message, which means it looks all nice and neat buffer and send
2-The reason output buffering was invented was to create a seamless transfer, from: php engine -> apache -> operating system -> web user
If you make sure each of those use the same buffer size, the system will use less writes, use less system resources and be able to handle more traffic.
With Regards, Hossein

cliff
good article on output buffering on devshed:
http://www.devshed.com/c/a/PHP/Output-Buffering-With-PHP

simon
Found that variables in class instances we're not being set after the call to ob_start().
Call ob_start after the variables are set however and it works but that didn't seem to solve the goal of a self contained templating class.
The fix was to assign the class by reference with '&new'
Here is a simplified working example:
<?php
class Buffer {
var $template = ' - template set in class constructor';
function Buffer() {
$this->startBuffer();
}
function startBuffer() {
ob_start(array(&$this, 'doFlush'));
}
function doFlush($buffer) {
/* simple string concat to show use of a
template string and the buffer output */
return $buffer . $this->template;
}
}
/* template does not get set:
$buffer1 = new Buffer();
$buffer1->template = ' - template set in instance';
echo 'some buffer content';
*/
/* this works as expected */
$buffer2 = &new Buffer();
$buffer2->template = ' - template set in instance';
echo 'some buffer content';

francois hill
Following clement dot ayme at st dot com 's remark :
In my experience it seems that the output IS buffered, but ALSO sent to the standard output !

anonymous
As a follow up to my previous post :
(output seems to go to standard ouptput in command  line mode even with the use of output buffering (ob_start) )
Setting implicit_flush to false seems to do the trick :
  ini_set('implicit_flush',false); // (avoids output even with    ob_start, in command line mode)
  ob_start();
  include (realpath(dirname(__FILE__))."/".$template);
  $ret_str.=ob_get_contents();
  ob_end_clean();
  ini_set('implicit_flush',true);
(See :
Chapter 43. Using PHP from the command line
)

kasper
Another way to make your code harder to copy, is to remove all line-breaks and tabs you have in it.
You can use this function to remove those.
You can choose to place "ob_start();" at the start of your main PHP-file, and "ob_end_clean();" at the end of it.
This is not the best solution though. If you are running Apache you might want to do something like this to a ".htaccess"-file:
php_value auto_prepend_file "/home/www/load_before.php"
php_value auto_append_file "/home/www/load_after.php"
(you should replace those files with files that actually exists).
In the "load_before.php" you can place the "ob_start();", and in the "load_after.php" you can do something like this:
<?
$html = strtr(ob_get_contents(), array("\t" => "", "\n" => "", "\r" => ""));
ob_end_clean();

echo $html;
?>
This will clean your HTML of all kind of linebreaks (both \n and \r) and tabulators (\t). This will save your users some bandwidth, but it will also make your HTML, JavaScripts and more very difficult to read or copy. That way, making it harder for people to steal your code if you do not want them to.
This isnt in the spirit of OpenSource, but anyway you should be aware that this is possible.
Be aware that if you use PHP-files, to simulate pictures, all linebreaks will also be remove, making them corrupt. A solution to this, could be to check the headers (Content-Type), and if isnt set, or it is "text/html", you can go ahead and remove the linebreaks and tabs.
At my site, with more than 50.000 pictures and about 60 people online, I couldnt see any difference in the loadtime.
But still be aware, that your output will not be sent, before the script is finished, which will make your page slower to load that way also, since it cannot send any output while loading, but will have to wait until the load is finished.

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