The trouble I am having is that depending on whether the user accesses my page using:

http://www.mypage.com

or

http://mypage.com

I get different results.

$_SERVER['SERVER_NAME'] recognizes the "www" as part of the domain name so it makes writing scripts based on this variable quite problematic.

I know it is possible to set a canonical URL through the .htaccess file but that doesn't seem a very robust solution. If the .htaccess file gets deleted, corrupted or whatever it screws up my PHP.

I want to know how I can strip out the "www" to get consistent results.

I suppose a Regex script is one solution but I was hoping there is a purely PHP solution.

After researching PHP array functions I came up with a script that seems to do the job. The reason for wanting this solved is that I am using a switch statement to serve up different Included content based on which domain name is used to access the files on my server.
There are two domain names with different TLDs pointed at the same site.

Here is the solution in case anyone is interested.

PHP Code:

<?php
//strips out the "www" from the server name
$hostName = $_SERVER['SERVER_NAME'];
$hostSlices = explode(".",$hostName);
if($hostSlices[0]=="www"){array_shift($hostSlices);}
$domain = join(".",$hostSlices);
//depending on which domain is used, different content is "included"
switch ($domain){
    case "mydomain.com":
        include ('american.inc.php');
        break;
    case "mydomain.co.uk":
        include ('british.inc.php');
        break;
    }
?>

if you have access to the apache virtualhost defiinition, there is a neater solution.
what I do is that I put an

setenv DOMAIN prod

in the vhost definition, and in my prepend initialisation stuff, I do a switch on

PHP Code:

$_SERVER['DOMAIN'] 


to get that value back.

I use this to have a generic db connection, and to switch the connection string depending of this variable.