PHP multilanguage - how to switch languages?

Question

Im trying to create a multilanguage website.I used this http://www.phpsimplicity.com/tips.php?id=15 tutorial and it works fine. But I don't understand how to switch languages and save it in session.

I have the menu:

<div id="language">
<ul>
    <li> <a title="LT" href="">LT</a></li> |
    <li> <a title="LV" href="">LV</a></li> |
    <li><a title="EN" href="">EN</a></li>|
    <li><a title="RU" href="">RU</a></li>
</ul>
</div>

For example, user pressed "EN" and how do I write this choice in session using href link?

Answer 1

This is a very simplistic example:

<?php
session_start();

$languages = array('LT', 'LV', 'EN', 'RU');

// handle language selection
if(in_array($_GET['lang'], $languages)) {
    $_SESSION['lang'] = $_GET['lang'];
}

// define LANG constant only if it exists in $languages array, otherwise default to EN
define('LANG', in_array($_SESSION['lang'], $languages) ? $_SESSION['lang'] : 'EN');

// do stuff with LANG constant


// display language options
foreach($languages as $language) {
    echo '<a href="?lang='.$language.'">'.$language.'</a>';
}

?>