[How-To]Multi-language Support to a PHP Website

Are you interested in having a multilingual website? This is a tutorial that shows you how you can do that in PHP.
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The first thing we need to do is to create a couple of files that will contain the text for each of the languages that will be supported by the website. For demo purpose I have chosen English, Spanish and German. Make a directory named �directory�. In this directory create 3 files: lang.de.php, lang.en.php, and lang.es.php. In our main file (index.php) we will include a file (common.php) containing a piece of code that gets the requested language. Here�s the content of those 3 language files:

lang.en.php

Code:

<?php
/*
------------------
Language: English
------------------
*/
 
$lang = array();
 
$lang['PAGE_TITLE'] = 'My website page title';
$lang['HEADER_TITLE'] = 'My website header title';
$lang['SITE_NAME'] = 'My Website';
$lang['SLOGAN'] = 'My slogan here';
$lang['HEADING'] = 'Heading';

// Menu

$lang['MENU_HOME'] = 'Home';
$lang['MENU_ABOUT_US'] = 'About Us';
$lang['MENU_OUR_PRODUCTS'] = 'Our products';
$lang['MENU_CONTACT_US'] = 'Contact Us';
$lang['MENU_ADVERTISE'] = 'Advertise';
$lang['MENU_SITE_MAP'] = 'Site Map';
?>

As you can notice, some constants are created using the define() function. In every file the defined constants have the same name, bu the values is different. We will output the values of the constants inside the index.php file. Therefore we will see different text every time we will call other language file.
Determine the right language

Let�s analyze the common.php file:

Code:

<?php
session_start();
header('Cache-control: private'); // IE 6 FIX

if(isSet($_GET['lang']))
{
$lang = $_GET['lang'];

// register the session and set the cookie
$_SESSION['lang'] = $lang;

setcookie('lang', $lang, time() + (3600 * 24 * 30));
}
else if(isSet($_SESSION['lang']))
{
$lang = $_SESSION['lang'];
}
else if(isSet($_COOKIE['lang']))
{
$lang = $_COOKIE['lang'];
}
else
{
$lang = 'en';
}

switch ($lang) {
  case 'en':
  $lang_file = 'lang.en.php';
  break;

  case 'de':
  $lang_file = 'lang.de.php';
  break;

  case 'es':
  $lang_file = 'lang.es.php';
  break;

  default:
  $lang_file = 'lang.en.php';

}

include_once 'languages/'.$lang_file;
?>

After we determine the value of $lang, we use switch() to compare its value with some different values, and execute a different piece of code depending on which value it equals to. After the value of the $lang_file is determined, the script will include the necessary language file. As you can see I have used sessions to register the value of $lang. This way users can navigate through the whole site and see the content in the chosen language (lang=[language here] does not need to be passed in every URL). Additionally, I have used cookies to store the selected language in users computer for 30 days. When the visitor will come back he will see the site in the language that he previously selected.
How if the website�s language requested?

In this demo I have chosen to use some image flags, each image having a link to index.php?lang=[LANG HERE]. So, to see the site in german we will use the German image flag which links to index.php?lang=de.

Lastly, the constants values should be outputted in the page. Examples:

for document title

Code:

<title><?php echo $lang['PAGE_TITLE']; ?></title>

for header menu

Code:

<ul>
     <li><a href="/"><?php echo $lang['MENU_HOME']; ?></a></li>
     <li><a href="about_us"><?php echo $lang['MENU_ABOUT_US']; ?></a></li>
  <li><a href="our_products"><?php echo $lang['MENU_OUR_PRODUCTS']; ?></a></li>
     <li><a href="contact_us"><?php echo $lang['MENU_CONTACT_US']; ?></a></li>
     <li><a href="advertise"><?php echo $lang['MENU_ADVERTISE']; ?></a></li>	
     <li><a href="sitemap"><?php echo $lang['MENU_SITE_MAP']; ?></a></li>
   </ul>

Thank you for checking on my topic.
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