How to know if a current page have parameter ?

Hello all,

I explain my problem : I have a website with 4 languages FR-DE-EN-IT and I want that when I click the language the current page need to be translated.

It's work when the page dont have any parameter.

with the page like this :
http://localhost:8888/contographie/index.php --> WORK
http://localhost:8888/contographie/index.php?lang=fr
But when i have this when I want to change to english :
http://localhost:8888/contographie/index.php?lang=fr?lang=en -> is not working :(

here the code

<?php

public function lnkLang_clic($strFormId, $strControlId, $strParameter){
            $currentPage = $_SERVER["REQUEST_URI"];
            QApplication::Redirect($currentPage.'?lang='.$strParameter);
    }

?>


The code in the prepend.inc

<?php
/////////////////////////////
        // Start Session Handler (if required)
        /////////////////////////////
        session_start();

        //////////////////////////////////////////////
        // Setup Internationalization and Localization (if applicable)
        // Note, this is where you would implement code to do Language Setting discovery, as well, for example:
        // * Checking against $_GET['language_code']
        // * checking against session (example provided below)
        // * Checking the URL
        // * etc.
        // TODO: options to do this are left to the developer
        //////////////////////////////////////////////
        if(isset($_GET['lang'])){
            $_SESSION['language_code'] = $_GET['lang'];
        }
        
        if (isset($_SESSION)) {
            if (array_key_exists('country_code', $_SESSION))
                QApplication::$CountryCode = $_SESSION['country_code'];
            if (array_key_exists('language_code', $_SESSION))
                QApplication::$LanguageCode = $_SESSION['language_code'];
        }
        else{
            QApplication::$LanguageCode = 'fr';
            $_SESSION['language_code'] = QApplication::$LanguageCode;
        }
        
        $langFile = __DOCROOT__ . '/lang/lang_' . QApplication::$LanguageCode . '.php';
        if(file_exists($langFile)){
            require_once($langFile);
        }
        else{
            require_once(__DOCROOT__ . '/lang/lang_fr.php');
        }
?>

I hope that you get my problem and can help me, I would be very thankfull :P

What I would like it's that if the page it's like this :
http://localhost:8888/contographie/index.php?lang=fr
if I click english I would like that “?lang=fr” is replaced by “?lang=en” and no add in the end like before.
OR
Never have this parameter visible “?lang=...” but I don't know how to manage the change of language without it

And if the page have parameter the “?lang=fr” is modified like this “&lang=fr” :D

Sorry for my bad english hope that I'm quite understandable with my problem

I would use QApplication::$ScriptName instead of QApplication::$RequestUri and add query string like in your first example.

ScriptName doesn't containt query string.

But this way you overwrite your query string so if you plan to send other parameters in your query string it won't work.

If you need to modify just lang parameter you could use http://php.net/manual/en/class.httpquerystring.php

Why not set $_GET['lang'] and then use QApplication::GenerateQueryString() ?

<?php
public function lnkLang_clic($strFormId, $strControlId, $strParameter){
            $_GET['lang'] = $strParameter;
            QApplication::Redirect(QApplication::$ScriptName.QApplication::GenerateQueryString());
    }
?>
.bc