Trouble connecting to MySQL using mysqli extension on XP

I had a tough time getting PHP to connect to MySQL using mysqli on XP. The following code from the php documentation on mysqli failed to work. $mysqli = new mysqli( "localhost", "user", "password", "database" ); Where localhost, user, password, and database were replaced with the appropriate values. I left the host parameter as "localhost" because that's what I wanted, however that did not work. So I changed it to NULL, which defaults to localhost as per the documentation, but this still did not work. After some googling, I found the answer on another forum, which stated that the host should be a dot ".", but no other explanation was given. Is there anyone that can shed some light on the situation? Everything works fine now, but I would really like to know why I can't use "localhost", and why this isn't documented. I've tried every mysqli option imaginable in the php.ini file. It seems that host must be a dot.