I am confused about something: Let's say I have a web application I've
developed and it's sitting in a directory called "Docroot". In that Docroot
folder is a Web.config and a Default.aspx.

Whe I run the application from within Visual Studio (2008), the URL in IE
when it runs is:
  http://localhost:2635/Docroot/Default.aspx
with the "Docroot" directory included in the URL.

But, of course, when I run it in IIS (outside of Visual Studio), the URL of
the "base" of the application will be
  http://localhost/Default.aspx
without the "Docroot" directory showing.

This poses a little problem for me in development:

Let's say I want to build my application so that I can rewite the URL of the
site from within the application based on runtime properties. The problem is,
I don't know how to rebuild the path of "~" because it'll be different if
it's running in VS as opposed to normally in IIS.

Is there a way to "know" this in runtime? And why *is* it different anyway?

Alex