ZEND PHP 5 Certification STUDY GUIDE

Chapter 3
Arrays
Arrays are the undisputed kings of advanced data structures in PHP. PHP arrays are
extremely flexible—they allow numeric, auto-incremented keys, alphanumeric keys
or a mix of both, and are capable of storing practically any value, including other
arrays. With over seventy functions for manipulating them, arrays can do practically
anything you can possibly imagine—and then some.
Array Basics
All arrays are ordered collections of items, called elements. Each element has a value,
and is identified by a key that is unique to the array it belongs to. As we mentioned
in the previous paragraph, keys can be either integer numbers or strings of arbitrary
length.
Arrays are created one of two ways. The first is by explicitly calling the array()
construct, which can be passed a series of values and, optionally, keys:
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
$a = array (10, 20, 30);
$a = array (’a’ => 10, ’b’ => 20, ’cee’ => 30);
$a = array (5 => 1, 3 => 2, 1 => 3,);
$a = array();
The first line of code above creates an array by only specifying the values of its three
elements. Since every element of an array must also have a key, PHP automatically