Quicksort - need help and code

[Robert Chao]

Can someone post C code for a simple Quicksort? I'm new at this and copied
a Quicksort pseudocode from a book into my C program. I noticed that the
pseudo code didn't include a check to keep i and j from running off the 
ends of the list (where i is the location of the value you are comparing
with the current key you want to place in its final position, and so is j).
(The book was a data structure book by Tremblay and Sorenson.)

Basically I understand Quicksort all right but I've never done it in code.
Are there different variations on Quicksort?

Thanks

Robert Chao