Programming PHP

EXTR_PREFIX_SAME, which says that the third argument to extract( ) is a prefix for the
variable names that are created. This helps ensure that you create unique variable
names when you use extract( ). It is good PHP style to always use EXTR_PREFIX_SAME,
as shown here:
$shape = "round";
$array = array("cover" => "bird", "shape" => "rectangular");
extract($array, EXTR_PREFIX_SAME, "book");
echo "Cover: $book_cover, Book Shape: $book_shape, Shape: $shape";
Cover: bird, Book Shape: rectangular, Shape: round
Creating an Array from Variables
The compact( ) function is the complement of extract( ). Pass it the variable names
to compact either as separate parameters or in an array. The compact( ) function creates
an associative array whose keys are the variable names and whose values are the
variable’s values. Any names in the array that do not correspond to actual variables
are skipped. Here’s an example of compact( ) in action:
$color = 'indigo';
$shape = 'curvy';
$floppy = 'none';
$a = compact('color', 'shape', 'floppy');
// or
$names = array('color', 'shape', 'floppy');
$a = compact($names);
Traversing Arrays
The most common task with arrays is to do something with every element—for
instance, sending mail to each element of an array of addresses, updating each file in
an array of filenames, or adding up each element of an array of prices. There are several
ways to traverse arrays in PHP, and the one you choose will depend on your data
and the task you’re performing.
The foreach Construct
The most common way to loop over elements of an array is to use the foreach
construct:
$addresses = array('spam@cyberpromo.net', 'abuse@example.com');
foreach ($addresses as $value) {
echo "Processing $value\n";
}
Processing spam@cyberpromo.net
Processing abuse@example.com
This is the Title of the Book, eMatter Edition
Copyright © 2002 O’Reilly & Associates, Inc. All rights reserved.
Traversing Arrays | 125