Class static variables reset when I call them in other file - php

Question

I am practicing PHP, and the issue I encountered today is my static variable getting reset every time I call it.
Login Page after verfied user from DB
<?php
Session::onlogin(1);
?>
This is my session class it has a func onlogin and I send some data to it from another file which change $is_signed to true. But the issue is variable $is_signed getting reset when I call it from index.php it returns false
<?php
class Session {
private static $is_signed = false;
function __construct(){
session_start();
}
public static function is_signed_in(){
return self::$is_signed;
}
public static function onLogin($userid){
if($userid){
session_regenerate_id();
$_SESSION['user_id'] = $userid;
self::$is_signed = true;
return true;
}
}
}
$session = new Session;
?>
Now I am calling it in index.php as below
if(Session::is_signed_in()){
echo "logged In";
}
else {
echo "error";
?>
I don't know where I am creating any error but when I call the methods.

Answer 1

So i asume this
class.php
class Session
{
private static $is_signed = false;
function __construct()
{
session_start();
}
public static function is_signed_in()
{
return self::$is_signed;
}
public static function onLogin($userid)
{
if ($userid) {
session_regenerate_id();
$_SESSION['user_id'] = $userid;
self::$is_signed = true;
return true;
}
}
}
$session = new Session;
login.php
<?php
require 'class.php';
$session = new Session;
Session::onlogin(1);
var_dump(Session::is_signed_in());// output true
index.php
<?php declare(strict_types = 1);
require 'class.php';
var_dump(Session::is_signed_in());// output false
think about it that login.php and index.php are 2 separate programs not aware one of each other.Thats why you try put SESSION there change
function __construct()
{
session_start();
if (isset($_SESSION['user_id'])){
self::$is_signed = true;
}
}
and you are done