do you create subdomains using PHP?

* Create the appropriate web root directory, for example /home/sites/username/web , and any subdirectories you wish
* Edit httpd.conf - add a new virtual host section
* Restart httpd

and also we can use another ways for this.

You can crate a virtual domain by using .htaccess file and you need to set some little things in control panel.
by using .htaccess file you can crate like as a under mention example.
http://www.domain.com/?a=user --> http://user.domain.com/