sessionlanguage.php

<?php
session_start();
// Start the session
//header file
$language = $_GET['lang'];

$languagestart = '?lang=';

$newlanguage = $languagestart.$language;

if((isset($language)) || (!empty($language))){

    //new language
    echo $newlanguage;

    // Set session variables
    $_SESSION["language"] = $newlanguage;
}


$actual_link = "http://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

echo $actual_link;

$a = '/?lang=';

if (strpos($a, $actual_link) !== false) {
    $b = 1; //in current url
} else {
    $b = 0; //not in current url
}

$new_full_link = $actual_link.$newlanguage;
//check if language is set but current page does not have language in URL
if (isset($_SESSION["language"]) &&  ($b == 1)){
    header("Location: $new_full_link");
}

?>