Unable to call the built in mb_internal_encoding method?

I’m trying to install indefero on a CentOS 5.3 VMware ‘box’ and I ran into a problem. Quite early in the installation I get an error that I’ve been able to narrow down to this:

[root@code /var/www/html]# cat x.php
 <?php
     mb_internal_encoding("UTF-8");
 ?>
[root@code /var/www/html]# php x.php
PHP Fatal error:  Call to undefined function mb_internal_encoding() in 
/var/www/html/x.php on line 2

I get the same error when calling this script via http through Apache. Now according to the PHP manual the mb_internal_encoding function should be a builtin in PHP 5.

I have CentOS 5.3 i386 (Linux code 2.6.18-53.1.21.el5 #1 SMP Tue May 20 09:34:18 EDT 2008 i686 i686 i386 GNU/Linux) and I’ve installed PHP 5.2.9.

[root@code /var/www/html]# php -v
PHP 5.2.9 (cli) (built: Jul  8 2009 06:03:36)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies

I double checked: selinux has been disabled (for now).

How do i fix this?

Answer

mbstring is a “non-default” extension, that is not enabled by default ; see this page of the manual :

Installation

mbstring is a non-default extension. This means it is not enabled by default. You must explicitly enable the module with the configure option. See the Install section for details

So, you might have to enable that extension, modifying the php.ini file (and restarting Apache, so your modification is taken into account)

I don’t use CentOS, but you may have to install the extension first, using something like this (see this page, for instance, which seems to give a solution) :

yum install php-mbstring

(The package name might be a bit different ; so, use yum search to get it 🙂 )