Difference with and without www, 301 redirect with codeigniter and htaccess

Question

I have a domain that shows different pages if I leave out the www. Without the www the page freezes, so I want to redirect the http://example.com to http://www.example.com

My question is, how do I change the htaccess so it redirects to the www version?

Here is my .htaccess:

DirectoryIndex index.php

RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond $1 !^(index\.php|robots\.txt)

RewriteRule ^(.*)$ index.php?/$1 [L]

Answer 1

A friend solved my problem by adding the following code underneath the existing code:

RewriteCond %{HTTP_HOST} !^$
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteCond %{HTTPS}s ^on(s)|
RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

Now everything works perfectly! The complete .htaccess file now looks like:

DirectoryIndex index.php

RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond $1 !^(index\.php|robots\.txt)

RewriteRule ^(.*)$ index.php?/$1 [L]

RewriteCond %{HTTP_HOST} !^$
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteCond %{HTTPS}s ^on(s)|
RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

Answer 2

Add these lines after RewriteEngine On:

RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

But keep in mind, making redirecting rule is just a compromise for your application, not solution for your page freezing problem.