Присвоение переменной свойству объекта

<?php
$object = new Users;
$object->name = $_POST['name'];
$object->password = $_POST['password'];
$object->save_users();
 
class Users
    {
        public $name, $password;
        
        function save_users()
        {
        global $name; $name =  ucfirst(strtolower($name));
        global $password; $password = ucfirst(strtolower($password));
        }
    }
 
echo $name . " " . $password;

echo $object->name . ' ' . $object->password;

<?php
$object = new Users;
$object->name = $_POST['name'] = 'vasya';
$object->password = $_POST['password'] = 'pupkin';
$object->save_users();
 
class Users
    {
        public $name, $password;
        
        function save_users()
        {
            $this->name =  ucfirst(strtolower($this->name));
            $this->password = ucfirst(strtolower($this->password));
        }
    }
 
echo $object->name . " " . $object->password;

<?php
$object = new Users;
$object->name = $_POST['name'] = 'вАНя';
$object->password = $_POST['password'] = 'pupkin';
$object->save_users();
 
  
    function mb_ucfirst($str, $encoding = "UTF-8", $lower_str_end = true) {
      $first_letter = mb_strtoupper(mb_substr($str, 0, 1, $encoding), $encoding);
      $str_end = "";
      if ($lower_str_end) {
        $str_end = mb_strtolower(mb_substr($str, 1, mb_strlen($str, $encoding), $encoding), $encoding);
      }
      else {
        $str_end = mb_substr($str, 1, mb_strlen($str, $encoding), $encoding);
      }
      $str = $first_letter . $str_end;
      return $str;
    }
  
class Users
    {
        public $name, $password;
        
        function save_users()
        {
            $this->name =  mb_ucfirst($this->name);
            
            $this->password = mb_ucfirst($this->password);
        }
    }
 
echo $object->name . " " . $object->password;