How to set a cookie for a domain in PHP?

Question

I want to set a cookie via PHP. The scenario is like this:

Domain is: example.com

There is one web page on sub-domain (my.example.com). My code is:

$value="I am looged in";
setcookie("TestCookie", $value,'','',".example.com");
echo "hello".$_COOKIE["TestCookie"];

but the result is only "hello" - the cookie is not getting set.

Answer 1

First two corrections to the actual call of setcookie: Parameter 3 (expired) should be an integer value (the default value is 0); parameter four should be set to '/' to make the cookie valid for all subdirectories; the setcookie call should therefore look like this:

setcookie("TestCookie", $value, 0, '/', ".example.com");

Then it should actually work the second time the script is called. To understand why it won't work the first time already, we have to dig in a little into how cookies work; basically, Cookies are data sent from the server to the client, where the server says "send me this data the next time you send me a request". That's basically what setcookie is for: When the request is done and the client has received and processed the page, the cookie as specified will have been created at the client; $_COOKIE, on the other hand, holds all values which are in cookies already, and which have been transmitted by the client along with the request - meaning that the first time the script is called, $_SESSION will actually still be empty, since the cookies will only be created once the client has received the scripts output.