Although it hardly counts as introductory material, I really like a book called Expect C Programming, by Peter van der Linden. The author worked on Sun's C comp

Although it hardly counts as introductory material, I really like a book called Expect C Programming, by Peter van der Linden. The author worked on Sun's C compiler, and has a lot of valuable insights into C. Basically, the book consists of a large list of "these are the things about C which will bite you." For example (please don't just Google for the answer): when is an array in C not equivalent to a pointer? The book contains a chapter on C++; plenty for a C programmer to get started. Unlike sources like the C++ FAQ, I don't believe it makes sense to treat C++ as a language separate from C, and I don't think a C++ programmer without a gut understanding of the semantics of C is a good C++ programmer.