and Arrays: Introduction
(Up to Basic
Lists and Array are the most basic types of data
structures. They allow the programmer to organize data into
more sophisticated patterns than the simple variables would allow.
Almost all programming languages are built-in with at least a simple
implementation of one or both of these, and the essays below deal
with expanding on these basic forms.
A list is just a grouping of data. Think of a shopping list
for groceries. It is simply a list of things to buy, but the list
is ordered, which means that the list (Bread,
Apples) is not the same list as (Apples,
An array is a kind of a list in which each object in an
array is assigned a specific number, called its index number,
and those numbers are used to locate and organize the objects. Thus,
an array of some famous poets might look like this:
||W. H. Auden
||T. S. Eliot
||e e cummings
Note: The array here starts with 0 as the first index number.
Theoretically, an array can start with any index number, but because
of the structure of computer memory, it is customary, and preferable,
to begin with 0 as the first index number.
Often, the elements of an array are sorted to speed up searches
through an array. This topic has been studied very thouroughly over
the years, and thus many algorithms
to sort arrays have been created.
Although arrays are the most common lists, there are other types
of lists as well. Two of the simplest and most useful are the stack
and the queue, both of which are used heavily
in operating systems and AI.
One very useful and versatile structure is the linked
list. The linked list is, unlike the array, a dynamic structure,
which means that it can resize itself when necessary.