Wordpress, get_current_user_id() returns 0 in a standalone php file

Question

This is my standalone php file

<?php
include('wp-blog-header.php');
header("HTTP/1.1 200 OK"); 

global $wpdb; $user_id ;
$user_id = get_current_user_id();
echo $user_id;
?>

The php is giving the result as 0. Even if I am logged in with Id 1.

Answer 1

Include the wp-load.php file in place of wp-blog-header.php with correct path.

<?php
include('wp-load.php');

global $wpdb; $user_id ;
$user_id = get_current_user_id();
echo $user_id;
?>

Answer 2

I tried your exact code on my system and it works as expected so there is nothing wrong with the code itself. Can you try

 <?php
include('wp-blog-header.php');
header("HTTP/1.1 200 OK"); 
var_dump( $_COOKIE );
global $wpdb; $user_id ;
$user_id = get_current_user_id();
echo $user_id;
?>

The var_dump() should display a line like:

'wordpress_logged_in_ ....

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