Setting custom cookies in WordPress

I am trying to set cookies to re-route returning users to my a specific page within my WordPress site.

I’d like some advice with these 2 things:

1. Where in the WordPress php files should cookies be checked before loading any content to handle a redirect? Is there a good file this should exist in over others?
2. How do I properly set a cookie within WordPress? setcookie('cookie_name', 'cookie_value', time()+4000); doesn’t seem to be saving any cookies to my system.

1 – You can check for cookies and do your redirect using hooks that are called before any output like the ‘init’ hook:

<?php

// Hook the function "redirect()" on to the "init" action
add_action('init', 'redirect');

// redirect() may redirect the user depending on the cookies he has
function redirect(){
  /* CODE */
}

?>

2 – The best way to set cookies would be using the ‘init’ hook like this:

<?php

add_action('init', 'my_setcookie');

// my_setcookie() set the cookie on the domain and directory WP is installed on
function my_setcookie(){
  $path = parse_url(get_option('siteurl'), PHP_URL_PATH);
  $host = parse_url(get_option('siteurl'), PHP_URL_HOST);
  $expiry = strtotime('+1 month');
  setcookie('my_cookie_name_1', 'my_cookie_value_1', $expiry, $path, $host);
  /* more cookies */
  setcookie('my_cookie_name_2', 'my_cookie_value_2', $expiry, $path, $host);
}

?>

This is more consistent, if you have a blog at www.example.com/blog, the coockie(s) will not be available at

• www.example.com
• www.example.com/store
• example.com
• www2.example.com
• …

Update

you should also be able to use the COOKIE_PATH and COOKIEDOMAIN constants rather than figuring them out yourself, which I just noticed in Andre R Kohl’s answer – drzaus