University of Minnesota, Twin Cities School of Statistics Stat 8701 Rweb
R-intro.html R-intro.pdf
R-exts.html R-exts.pdf
Do not print copies of these on department laser printers! The department staff will get mad at you if you do.
A paper copy for photocopying can be obtained from the department office and is also at Copies on Campus in the basement of Johnson Hall.
The standard reference is K & R (see also at the publisher's web site). But many find this too elegant and austere. It is the right book if you are already an experienced programmer.
A more user-friendly reference is the pink cow book.
If you already know C or have a book about C, there is no need to buy a book.
I have put my copy of the pink cow book in the lab, so you can use it there if you will be doing most of your programming in the lab.