为什么这个cookie不起作用？

Question

My site have a full version and a mobile version. When type the URL, the index.php will detect user's client to direct to full version or mobile version. This works fine. Users from desktop client can also switch to mobile version. But I have trouble for users from mobile client switching to full version. The codes are here:

// index.php
<?php
$useragent=$_SERVER['HTTP_USER_AGENT'];
if(preg_match('...',substr($useragent,0,4))) {
  $type = 'mobile';
} else {
  $type = 'full';
}
if ($type == 'mobile' and $_COOKIE['switch'] != 'full') {
  header ('Location: m/');
} else {
  include './front.html.php';
}
?>

// m/switch.php  page when user click
<?php
setcookie('switch', 'full', time() + 60);
header('Location: ../');
?>

I have also reversed the order of setcookie and header , but still doesn't work.

Is it possible cookie is forbidden in mobile device?

* Update *

I added a $type = 'mobile'; before the condition, so that no matter what client, it is assumed to be mobile. Then I used Chrome from my laptop to test, and the cookies are definitely enabled. It goes to mobile version (ok), but click switch still does not go to full version. So it is problem of the cookie itself.

Answer 1

You need to specify the path of the cookie

setcookie('switch', 'full', time() + 60, '/');

From the manual we can know

http://php.net/manual/en/function.setcookie.php

The path on the server in which the cookie will be available on. If set to '/', the cookie will be available within the entire domain. If set to '/foo/', the cookie will only be available within the /foo/ directory and all sub-directories such as /foo/bar/ of domain. The default value is the current directory that the cookie is being set in.

In you example the script switch.php will set the cookie in the path /m/ (default value is the current directory). However your index.php was trying to read cookie form / , thus the redirection will fail.