It is very easy to make sure that a user uses http://www.domain.com instead of just http://domain.com with a simple piece of PHP code placed at the top of every page.
Courtesy of sdjl
You can also use mod_rewrite in your .htaccess file. Put it inside your public_html directory in order for the changes to effect all files/directories.
Replace domain and .com as necessary.
Courtesy of ndns
PHP Code:
<?php
$server = getenv("HTTP_HOST");
if (!ereg("^www.", $server)) {
// Assume no www. has been entered
Header ("Location: http://www.".$server."/");
Exit;
}
?>
You can also use mod_rewrite in your .htaccess file. Put it inside your public_html directory in order for the changes to effect all files/directories.
Code:
RewriteEngine On Options +FollowSymlinks RewriteCond %{HTTP_HOST} ^domain\.com RewriteRule ^(.*)$ http://www.domain.com/$1 [R=permanent,L]
Courtesy of ndns