How do I write a float to a file, that is, not store it but print a numeric valie?
I've managed to create and write to a file, so no problems there. Printf writes numbers to the console, but I'm not sure if I can use that to write to a file...

Use wsprintf from user32.dll
wsprintfW (Unicode) and wsprintfA (ANSI)
http://msdn.microsoft.com/en-us/library/ms647550%28v=vs.85%29.aspx

It will format to a buffer instead of the console.
*** edit *** oops wsprintf doesn't format floating point

Use sprintf from msvcrt.dll instead of printf

That did the trick, thanks a lot!