为什么此PHP setcookie（）参数未设置cookie？

Question

I have this PHP

setcookie('hello', '0', 0, '/389732/');

Why when I run it does it not set a cookie?

I printed the value of $_COOKIE['hello'] out immediately after and it puts out an error because it does not exist.

Answer 1

setcookie documentation spells this out:

Once the cookies have been set, they can be accessed on the next page load with the $_COOKIE ...

Edit: it might be tempting to manually insert that cookie into $_COOKIE yourself, but keep in mind that some frameworks helpfully parse $_COOKIE into other data structures on startup and will not see such hackish changes.

Answer 2

$_COOKIE gets populated when the script first runs. setcookie puts the cookie info in a queue that gets turned into a header when the page returns to the browser.

When the browser requests a new page, it sends the cookie information back to your server and the $_COOKIE variable will be populated.

Answer 3

因为$ _COOKIE是调用php时cookie的内容。