M. Sokolewicz wrote:
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.
I'll keep the ob_end_flush just for showing what's going on, but thanks
for the hint.
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).
Thanks, now it's understandable.
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@xxxxxxxxxxxxx list.
- Tul
O. Wyss
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