Re: Cookies and sent headers

On a sidenote, 99% of the world never calls ob_flush (or any such function) since PHP flushes the buffer automatically at the end of its execution. The reason why setting cookies for you doesn't work is because of the way a HTTP response is structured. It consists of 2 parts: header and body separated by 2 new lines (\n\n). It is _required_ that _all_ headers come _before_ the body. Cookies are actually headers (a set-cookie: [...] header) aswell as any headers set via php's header() function. Any output made by the script (be it a single whitespace, a bunch of text, etc.) will automatically flush the headers, followed by the separator (\n\n) followed by the specified output. After that has been sent, everything outputted will be dumped into the body of the response (simply because you can't "go back" to the headers which were already sent earlier), so you can't set cookies (which are headers themselves). So, why does output buffering help here? Simply put, instead of dumping headers and any other output directly to the client, PHP buffers it all into memory. As such, since it hasn't been sent yet, PHP can still alter/add headers even though it also has body-output. Once it receives the command, PHP will send all headers, the separator and the output to the client. This is done when PHP encounters an ob_flush or ob_end_flush call, _and_ when the script has finished execution automatically. The documentation seems pretty clear to me, however, if you feel it should be clarified better, feel free to send a patch to the php-doc@lists.php.net list. - Tul Bastien Koert wrote:

The commands start and use an output buffer, a chunk of memory that stores all the output on the server until the ob_flush, the buffer flush, function is called. You need to be aware that in high load situations this may adversly affect performance since it loads the servers memory, also be aware that you may hit a memory limit for large pages. This is server / OS depandant so you may want to read up on server documentation bastien ----------------------------------------

To: php-general@lists.php.net; wouter@interpotential.com Date: Sat, 18 Aug 2007 16:39:29 +0200 From: otto.wyss@orpatec.ch CC: kelvinpark86@gmail.com; php-general@lists.php.net Subject: Re: [PHP] Cookies and sent headers ob_start() at the beginning and ob_end_flush() at the end of the PHP section seems to do the trick albeit I've still problems to understand why. The description in the manual is rather sparse unfortunately. Is there any more information about what's going on? O. Wyss Wouter van Vliet / Interpotential wrote:

You best option would be to go through all of your include'd or require'd files and make sure there is no whitespace before and after you open your php tags. Those are often the cause for such problems. The easy way would indeed be to use output buffering. In that case, put the call to ob_start(); on the first line of the file you're calling. You will still have to make sure to not have any whitespace before your > To even bypass that, the output_buffering ini setting might be useful. Alter it in your php.ini if you can, otherwise try your apache vhost configuration or .htaccess. The syntax there is:

     php_flag output_buffering On

Good luck! On 18/08/07, Kelvin Park wrote:

Kelvin Park wrote:

Otto Wyss wrote:

If built a simple login page and store any information within $_SESSION's. Yet I'd like to move these into cookies but I always get an error about sent headers. Is there a way to circumvent this problem without changing too much in the page? The setting of the cookies happens just at the end of the page. if (!$errortext and $Anmelden) {

    if (!empty($Permanent)) {
      $expires = time()+ 365 * 86400;  // 365 days
      setcookie ("l.Lastname", $_SESSION['l_Lastname'], $expires);
      setcookie ("l.Firstname", $_SESSION['l_Firstname'], $expires);
      setcookie ("l.Email1", $_SESSION['l_Email1'], $expires);
      setcookie ("l.Email2", $_SESSION['l_Email2'], $expires);
    }
    echo "";
    exit;

} O. Wyss

ob_start() might help

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