Multilingual site PHP switching method - php

Question

I'm trying to figure out, what I am missing to make two lingual website for PHP pages.
In the root folder, I have index.php and other PHP files along with the include folder, which contains lang-switch.php, navbar.php with other PHP files, footer.php, header.php, etc. navbar.php contains:
<li class="nav-item">
<a class="nav-link" href="?lang=en">En</a>
</li>
<li class="nav-item">
<a class="nav-link" href="?lang=es">Es</a>
</li>
and lang-switch.php:
if (!isset($_SESSION['lang'])){
$_SESSION['lang'] = "en" ;
}else if (isset($_GET['lang']) && $_SESSION['lang'] != $_GET['lang'] && !empty($_GET['lang'])){
if($_GET['lang']){
$_SESSION['lang'] = "en";
} else if ($_GET['lang'] == "es") {
$_SESSION['lang'] = "es";
}
require_once "languages/" . $_SESSION['lang'] . ".php";
}
in the root folder, I also have the languages folder with two files en.php:
$lang = array(
"home" => "Home",
"aboutus" => "About Us",
"contactinfo" => "Contact Information",
"nodatafound" => "No Data Found",
);
and es.php:
$lang = array(
"home" => "Principal",
"aboutus" => "Sobre",
"contactinfo" => "Información del contacto",
"nodatafound" => "Datos no encontrados",
);
then in footer.php, which is in the same includes folder, I include:
include('lang-switch.php');
to pass in html tag:
<div><?php $lang['home'] ?> </div>
<div><?php $lang['aboutus'] ?></div>
I got:
Notice: Undefined variable: lang in
C:\xampp\htdocs\user\site\includes\footer.php on line 16
Notice: Undefined variable: lang in
C:\xampp\htdocs\user\site\includes\footer.php on line 17
with using <?php echo $lang['home'] ?>:
Warning: Illegal string offset 'aboutus' in
C:\xampp\htdocs\user\site\includes\footer.php on line 25
Warning: Illegal string offset 'home' in
C:\xampp\htdocs\user\site\includes\footer.php on line 26

Answer 1

Something like this would probably work for you. I tried to add comments to make it as clear as possible.
Also, this assumes you are using PHP 7.4+ and that you are running session_start() somewhere before this code starts.
I did not test this at all, but is should at least give you a start.
navbar.php
<li class="nav-item">
<a class="nav-link" href="?lang=en">En</a>
</li>
<li class="nav-item">
<a class="nav-link" href="?lang=es">Es</a>
</li>
functions.php or helpers.php or whatever you want
<?php
/**
* Get the current session language
*
* #return string
*/
function getLanguage()
{
// default to 'en' if no language is set yet
return $_SESSION['lang'] ?? 'en';
}
/**
* Set the language based on the `lang` url param
*
* #return void
*/
function setLanguage()
{
$known_languages = [
'en',
'es'
];
// make sure $_GET['lang'] is not empty
// and make sure the new language is known to us
if ( !empty($_GET['lang']) &&
$_SESSION['lang'] !== $_GET['lang'] &&
in_array( $_GET['lang'], $known_languages )
) {
$_SESSION['lang'] = $_GET['lang'];
}
}
/**
* Get the $lang variable with all the translated strings
* This should probably be a JSON file or something similar
*
* #return array
*/
function getTranslations() {
include "languages/" . getLanguage() . ".php";
/* #var array $lang*/
return $lang;
}
/**
* Get the translated string from our list of translations
* Print a translation missing message if not found
*
* #param string $string
* #return string
*/
function getTranslatedString( $string ) {
$string_values = getTranslations();
return $string_values[$string] ?? "Not Translated ( $string )";
}
/**
* Prints the translated string from our list of translations
*
* #param string $string
* #return void
*/
function printTranslatedString( $string ) {
echo getTranslatedString( $string );
}
The translation files stay as you have them, even though you may probably make use of JSON or something similar.
Then, you should run the setLanguage() function somewhere before the output of your HTML starts otherwise you will end up with warnings like:
Warning: Cannot modify header information - headers already sent by
(output started at ...
And then, in your HTML you should be able to use it like:
<div>
<a href="index.php" class="text-dark">
<?php printTranslatedString('home') ?>
</a>
</div>
<div>
<a href="about_us.php" class="text-dark">
<?php printTranslatedString('aboutus') ?>
</a>
</div>