Force WWW in .htaccess without having the domainname

Question

Hi,

I'm searching for some rewriterules to do this:

• Force a user to use WWW if he hasn't given an subdomain (so other subdomains should be working)
• If it's a HTTP or HTTPS connection, the script is still working
• If the url is 'example.nl', 'example.de', 'whatanexample.com' or something other, the same script is working in all this cases.

I had a script that worked for me but the other way (non-WWW) but trying to change it to force WWW isn't working for me.

Thanks on beyond.