First of all, when you use "first of all", there needs to be a second or next thing. Next, this has nothing to do with it being a varadic function, and everything to do with the format specifier he's using. Finally, it's good to finish up with a "finally", or maybe a "last but not least".
To the OP, read: http://c-faq.com/aryptr/index.html
Quzah.