I’ve got XAMPP installed on a Windows 7 machine. I wanted a way to test multiple sites locally.

Set up the local host file

In your host file, add (replace with the domains you want):

127.0.0.1    sub.domain.com.dev
127.0.0.1    www.example.com.dev
127.0.0.1    www.unfocus.com.dev

Set up XAMPP config files

In \xampp\apache\conf\httpd.conf uncomment the following at about line 140:

LoadModule vhost_alias_module modules/mod_vhost_alias.so

I’ve used the folder structure of “\xampp\htdocs\www.example.com\web\content\files.php” (for example) and the following config will find the folder with the exact name in the url.

In \xampp\apache\conf\extra\httpd-vhosts.conf:

NameVirtualHost *:80

<virtualhost *:80>
    DocumentRoot C:/xampp/htdocs/
</virtualhost>

<virtualhost *:80>
    VirtualDocumentRoot C:/xampp/htdocs/%-2+/web/content/
    ServerAlias *.dev
    php_admin_value auto_prepend_file C:/xampp/setdocroot.php
</virtualhost>

Fix DOCUMENT_ROOT

Create setdocroot.php at “\xampp\” and put the following in it:

<?php  $_SERVER['DOCUMENT_ROOT'] = str_replace($_SERVER['SCRIPT_NAME'],"",$_SERVER['SCRIPT_FILENAME']);  ?>

References:
https://issues.apache.org/bugzilla/show_bug.cgi?id=26052#c27
http://stackoverflow.com/questions/138162/wildcards-in-a-hosts-file
http://postpostmodern.com/instructional/a-smarter-mamp/