Re: Cookies problems - why do they need special treatment?

On Mon, 13 Aug 2007 11:35:59 +0200, ofiras <ofiasu@xxxxxxxxx> wrote:

Hii everyone,
I've been programming in php for a long time, and the cookies have
always been a trouble for me.
When I have headers before the cookies set, I get a problem.
Even if I leave space on the first row before I set the cookie, and
there is nothing else,
It says I have headers before.
Is it like that for everyone, or is it just my host?
If so, is there anything that I can do to set cookies anywhere I want?


Read up on the HTTP protocol. A response of a server is divided into headers & body (not to be confused with an HTML head & body). Something like this:

(header)
200 OK
Content-length: xxx
(...more headers)

(empty line, followed by body)
<!DOCTYPE html>
<html>
....etc

As your script produces (non-header) output, the empty line, which seperates the headers from the body of the response, is sent to the browser, followed by whatever output you specified further. A cookie has to be set in the headers (with a Set-Cookie statement), and there's no way of going back as soon as this empty line has been sent.

If you have to set a cookie somewhere, consider these options:

1. Do almost all processing _before_ generating output. As soon as you get out of an HTML mindset (and those atrocious files mixing HTML & PHP like there's no tomorrow) this is actually quite easy.

2. Capture output in a variable, and only echo / print it as soon as you know no further processing/header() or setcookie() calls are needed.

3. Turn on output buffering (ob_start()) at the start of the script. (Which will effectively do something like (2) only with somewhat less control).

The last one is a bit of cheat, and does not promote good code writing. It is however most simple one. Drawback is that on a slow loading page, it will take a while to get even a bit of content, while with output buffering of it can load 'as you go' (depending on how your browser handles it offcourse). If possible, go for (1).
--
Rik Wasmus
.

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