An introduction to programming in C. This seems to have a pretty thorough introduction, and includes quizzes after many sections of the tutorial, and also lists of books and other resources if you're interested. Highly recommended.
An introduction to programming in C++. This is another very good, C++-specific tutorial. This site (cplusplus.com) also has a pretty complete online function list for the standard libraries, which is helpful if you need to look something up while programming.
Recommended course textbook.