<p>Is it possible to configure <a href="http://www.apachefriends.org/en/xampp.html" rel="noreferrer">xampp</a> to serve up a file outside of the <code>htdocs</code> directory?</p>

<p>For instance, say I have a file located as follows:</p>

<p><code>C:\projects\transitCalculator\trunk\TransitCalculator.php</code></p>

<p>and my <a href="http://www.apachefriends.org/en/xampp.html" rel="noreferrer">xampp</a> files are normally served out from:</p>

<p><code>C:\xampp\htdocs\</code></p>

<p>(because that's the default configuration) Is there some way to make Apache recognize and serve up my <code>TransitCalculator.php</code> file without moving it under <code>htdocs</code>? Preferably I'd like Apache to serve up/have access to the entire contents of the projects directory, and I don't want to move the projects directory under <code>htdocs</code>.</p>

<p>edit: edited to add Apache to the question title to make Q/A more "searchable"</p>

You can set Apache to serve pages from anywhere with any restrictions but it's normally distributed in a more secure form.
Editing your apache files (http.conf is one of the more common names) will allow you to set any folder so it appears in your webroot.
EDIT:
alias myapp c:\myapp\
I've edited my answer to include the format for creating an alias in the http.conf file which is sort of like a shortcut in windows or a symlink under un*x where Apache 'pretends' a folder is in the webroot.  This is probably going to be more useful to you in the long term.