add a sub domain?

Is there anyway i can add a sub domain through php, like i have a domain name say, www.mysite.co.uk redirected to my home server, well i want a subdomain.mysite.co.uk

so in peusdo,

header(location: subdomain.mysite.co.uk);

which wouldn't make any sense as it would have to do a dns lookup for that url. Thing is i've registered a domain name but can't seem to add any subdomains for it, dont think they support it though not clear at all, no tech support for that section, so thought i could 'hack' one.
?

You need to add the subdomain though host. You would need to speak to your host as there is no way to "hack" one onto your site.

John, this can be done through PHP.
Although, its not a great way to do it, I'll dig up an old script that I used to use:...
http://www.aprelium.com/forum/viewtopic.php?t=1081

That only works if the host is setup so *.domain.com points to your site. Most hosting I have seen only allow domain.com and www.domain.com to point and make you setup subdomains yourself.

True, but I thought I would just throw it out there. As I use several domains, I used to use that script (until I discovered Apache xD).