# Chapter 2 (Array-based lists)

These data structures have common advantages and limitations:

* constant-time access

* resizing the array adds potentially non-trivial complexity, both in time and
  storage, as a new array generally must be created and the old array copied
  over.

* arrays aren't dynamic, which means inserting or deleting in the middle of an
  array requires shifting all the following elements.

With some careful management, the additional *amortised* complexity added by
resizing isn't too bad.

## Array stack

* Uses backing array *a*.
* Typically, the array will be larger than necessary, so an element *n* is
  used to track the actual number of elements stored in the stack.