Php 如何从不同文件中的类中获取变量的值？

我有一个user.php（class）、login.php和index.php。当我在index.php中提交表单时，表单操作转到login.php，该文件使用用户类验证是否存在试图登录的用户。如果为true，请再次重定向到index.file。但我想在用户登录时将其全名写入index.php。但我不能从课堂上取全名

注意：在require_once中，部分代码包括必要的文件，如database.php、session.php、functions.php等。因此，它们没有错误，我的函数也没有错误。我想要的是当用户登录时如何将全名写入index.php。

下面是user.php：

require_once $_SERVER['DOCUMENT_ROOT'].'/includes/database.php';

class User{

protected static $table_name="users";
protected static $db_fields = array('id', 'email', 'password', 'first_name',
'last_name');

public $id;
public $email;
public $password;
public $first_name;
public $last_name;

public function full_name() {
if(isset($this->first_name) && isset($this->last_name)) {
  return $this->first_name . " " . $this->last_name;
} else {
  return "";
 }
}

public static function verify($user, $email="", $password="") {
global $database;

$sql  = "SELECT * FROM users ";
$sql .= "WHERE email = '{$email}' ";
$sql .= "AND password = '{$password}' ";
$sql .= "LIMIT 1";
$result_array = self::find_by_sql($sql);

    if (!empty($result_array)) {
        $user->first_name =  $result_array['first_name'];
        $user->last_name =   $result_array['last_name'];
        return array_shift($result_array);
    } else {
        return false;
    }
 }  

$user = new User();
//User class continue but i inserted necessary parts. All functions in the class works.

下面是login.php：

<?php require_once  $_SERVER['DOCUMENT_ROOT'].'/includes/initialize.php'; ?>
<?
if($session->is_logged_in()) {
redirect_to("index.php");

}

if (isset($_POST['submit'])) {

$email = trim($_POST['email']);
$password = trim($_POST['password']);


$found_user = User::verify($user,$email, $password);

if ($found_user) {
$session->login($found_user);

    redirect_to("index.php");

} else {

$message = "There is error about username/password";
echo $message;
}

} else {
$email = "";
$password = "";
} 
?>

下面是index.php：

<?php require_once  $_SERVER['DOCUMENT_ROOT'].'/includes/initialize.php'; ?>

<?php

if($session->is_logged_in()) {
echo $user->full_name();

} else {
echo "No name";
}



?>

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将全名的输出保存到会话变量中。然后可以调用它来复制名称

有关在PHP中使用会话的信息，请使用手册：