What are Iterators, C++?

Question

What are Iterators in C++?

Answer 1

Though it initially seems fairly obvious, this is actually a rather deeper question than you may realize. Along with Paul McJones, Alexander Stepanov (designer of the original, for anybody who's not aware of that) recently released a book named Elements of Programming (aka EOP). The entirety of chapter six in that book is devoted specifically to iterators, and quite a bit of the rest of the book relates closely to iterators as well. Anybody who really wants to know iterators in full detail might consider reading this book.

Warning: EOP is not for the faint of heart. It's relatively short (~260 pages), but quite dense. Speaking from experience, the early going is a bit disconcerting. My initial reaction to the first chapter was more or less "well, this is so obvious it's hardly worth reading. I did start programming before last week, after all!"

Fortunately, I did look at the exercises, and tried to do a couple -- and even though I had thought of the subjects as obvious, the exercises demand rigorous proofs. It's a bit like being asked to prove (in a mathematical sense) that water is wet. You end up just about needing to read the chapter a couple of times just to get past your own preconceived notion that you already know the answers, so you can look at the real question -- what does "wet" really mean; what are the fundamental characteristics of "wetness"?