How do you update a cookie in PHP?

Question

If I call setcookie() two times with the same cookie name, I get two cookies created.

How do you update an existing cookie?

Answer 1

You can update a cookie value using setcookie() function, but you should add '/' in the 4th argument which is the 'path' argument, to prevent creating another cookie with the same name.

i.e. setcookie('cookie_name', 'cookie_value', time()+3600, '/');

A suggested expiration time for the 3rd argument:

• $exp_time = time()+3600; /* expire in 1 hour */
• $exp_time = time()+86400; /* expire in 1 day */

Answer 2

You can't update a cookie per se, you can however overwrite it. Otherwise, this is what you are looking for: http://php.net/manual/en/function.setcookie.php

It works. Be sure to read "Common Pitfalls" from that page.

You can use the super global $_COOKIE['cookie_name'] as well to read cookies.

Answer 3

Make sure there is no echo before setcookie call. setcookie communicates with browser through header, and if you called echo earlier, header+body is sent already and server cannot send setcookie to browser via header anymore. That is why you might see it is not working.

There should be a line like below in php server log file reporting warning in this case:

DEFAULT: PHP Warning:  Cannot modify header information - headers already sent by (output started at /path/to/your/script.php:YY) in /path/to/your/script.php on line XX