CProgramming.com
is one of the best places to learn C is.
It has clear and concise tutorials about
- Basics of C ( loops , pointers recursion etc.)
- Data structures (linked lists,binary trees etc. )
- OpenGL for graphics
- Tips and Tricks
- Code Snippets
- and even AI (neural networks)
They also have small Quiz at the end of each chapter.
The K & R is simply the best (but I guess you wanted some online tutorial).
