Using iterators
An iterator is a special type of class that allows you to traverse a container or list. The keyword here is traverse. What this means is that the iterator provides the means to go through a list, but it does not perform the traversal itself.
The SPL provides a rich assortment of generic and specialized iterators designed for different contexts. The ArrayIterator, for example, is designed to allow object-oriented traversal of arrays. The DirectoryIterator is designed for filesystem scanning.
Certain SPL iterators are designed to work with others, and add value. Examples include FilterIterator and LimitIterator. The former gives you the ability to remove unwanted values from the parent iterator. The latter provides a pagination capability whereby you can designate how many items to traverse along with an offset that determines where to start.
Finally, there are a series of recursive iterators, which allow you to repeatedly call the parent iterator. An example would be RecursiveDirectoryIterator...
