Is there any online reference for iostream?
Just look for a standard C++ library reference. SGI, dinkumware and MSDN have one. Or better yet, get a beginning C++ book.
"Standard C++ IOStreams and Locales" by Langer & Kreft is a very good book on these rather neglected areas of the standard C++ library.
All the buzzt!
"There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
- Flon's Law