multi language site PHP ,illegal offset string - php

Question

Hello i am facing a problem which is really confusing me when I want to print the strings stored in the array . I have
Warning: Illegal string offset 'TITLE' in C:\xampp\htdocs\site1\index.php on line 443
...
Actually the site is multi language and i want to display diffenet languages upon the desire of the user. What is the origin of this problem ?
<?php
include_once 'common.php';
?>
<form method="get" name="signup" >
<h1 id="head"></head></br>
<h1 ><?php echo $lang['USER_REGISTRATION']; ?></h1>
<h4 id="req">*Donates Required Fields</h4>
<table>
<tr>
<td><?php echo $lang['TITLE']; ?>:*</td>
<td><input type="text" name="title"/></td>
</td>
</tr>
</table>
</form>
<?php
session_start();
header('Cache-control: private'); // IE 6 FIX
if(isset($_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 'pr':
$lang_file = 'lang.pr.php';
break;
case 'ar':
$lang_file = 'lang.ar.php';
break;
default:
$lang_file = 'lang.en.php';
}
include_once 'languages/'.$lang_file;
?>
$lang['USER_REGISTRATION']="User Registration";
$lang['TITLE']="Title";

Answer 1

This error means that $lang does not have the key and value of TITLE. To check what keys and values an array has use var_dump(). You need to define $lang['TITLE'] before echo'ing.

Answer 2

As the error message clearly says, $lang is a string, not an array. Total shot in the dark here:
Your include_once is not including the file, because you've already included it elsewhere and it's not being included a second time due to the _once. That, or that file does not exist, in which case you need to check your error logs.

Answer 3

$language='ru';
if ($language=='ru') {
$lang['Add']='Добавить';
$lang['Back']='Назад';
$lang['Cancel']='Отмена';
$lang['Date']='Дата';
$lang['Days']='Дней';
$lang['Upload']='Загрузить';
$lang['Value']='Значение';
$lang['Hello']='Привет';
}
/* Functions */
//translation
function __($text){
global $lang;
if (isset($lang[$text])){ return $lang[$text];}
else {return $text;}
};
echo __('Add');