How to put 2 languages ​​on the site?

Question

PHP

How can I load the language file when choosing a language
1-file - ru.php in the file <?php define('L1', 'Main'); ?>
2- file - en.php in file <?php define('L1', 'Home'); ?>

print "<a href='test.php?language=en'>EN</a> | <a 
 
href='test.php?language=rus'>RUS</a>";
 
$language=....
 
if($_GET['language']==$language)
{
include"выбранный язык";
 
print $переменная;
}

Well, on the website:

<p><?=echo L1; ?></p>  Должна меняться при выборе языка

Answer 1

try u modifier , @ui

Answer 2

php.net/manual/en/function.gettext.php