Linked list

Programming basics

Arrays are a fundamental data structure, and they are extremely useful. We use arrays to hold values of the same type at contiguous memory locations. In particular, the use of arrays allows us to create "groups" or "clusters" of variables without needing to give a unique variable name to each, but still allowing us to individually index into the elements of the array. If you haven't started counting from zero yet, now is the time, because in C, arrays are zero-indexed which means the first element of a k-element array is located at array index 0 and the last element is located at array index k-1. In case you're wondering, that's the primary reason we count from 0 in CS50 (and in computer science more broadly!)

In an array we are usually concerned about 2 things, the position (or the index) of an element and the element.

An example of a simple array in PHP can be found below:

<?php
# this file  is used to teach the VERY BASICS of arrays in PHP

$pizza_toppings = [
"extra cheese",
"onions",
"pepperoni",
"ham",
"pineapple",
"chicken",
"arugula",
"pesto"
];

# This creates a very simple array with 8 items. 

?>

singly linked list

This video discusses the C programming language, but the content is clear to describe linked list.

Standards

• Describe how linked lists operate logically.
• Sketch linked lists (single, double and circular).

See Also

• abstract data types

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Represent by means of a diagram or graph (labelled as appropriate). The sketch should give a general idea of the required shape or relationship, and should include relevant features.