ITM 352 1

ITM 352

Array Processing

ITM 352 2

Simple Array ProcessingArrays can be processed using iteration.

Standard array-processing loop:

What about associative arrays?

for ($i=0; $i < count($angles); $i++) { print "angle $i: ". $angles[$i];}

foreach ($products as $key => $value) { print 'key ' . $key . ' has value ' $value;}

Do Lab #1

ITM 352 3

Multi-dimensional Arrays Arrays can hold any PHP data type including other

arrays This is useful for creating multi-dimensional

arrays$row1 = array('a','b','c');$row2 = array('d','e','f');$row3 = array('g','h','i');// make 2-dim array of rows$matrix = array($row1, $row2, $row3);

echo $matrix[0][0];echo $matrix[1][2];echo $matrix[2][1];$matrix[2][2] = 'I';

ITM 352 4

Multi-dimensional Arrays (cont.)There's no reason you cannot mix indexed

and associative arrays (you will find this useful later)

$product1 = array('name' => 'small gumball', 'price' => 0.02);$product2 = array('name' => 'medium gumball', 'price' => 0.05);$product3 = array('name' => 'large gumball', 'price' => 0.07);

// array of all products$products = array($product1, $product2, $product3);

for($i=0; $i<count($products); $i++) echo "Product: $i is {$products[$i]['name']} and costs {$products[$i]['price']} each<br>";

Do Lab #2

ITM 352 5

Element Existence Sometimes it's useful to know an element exists in

an array. Use the array_key_exists() function for this:$product = array('name' => 'small gumball', 'filling' =>

NULL, 'price' => 0.04);if( array_key_exists('name', $product) )

echo "Product is {$product['name']}";

Why not just use isset()?array_key_exists('filling', $product) // returns?

isset($product['filling']) // returns?

Do Lab #3

ITM 352 6

Searching

You can test for an element in array with in_array()

if (in_array('small gumball', $product))print('we sell small gumballs');

You can search for an element key by value in an array with array_search()

print "the key for small gumball is " . array_search('small gumball', $product);

Do Lab #4

ITM 352 7

Sorting

There are many ways to sort the elements in array such as sort(),asort(),ksort():

$a = array('3', 'a', 'c', 'b', '2', '1');sort($a);

See LP, p. 60 or use the on-line manual at php.net Take care with sorting functions as they do not return

the sorted array. The array is directly manipulated (the parameter is passed by reference).

ITM 352 8

Keys and Values$product = array('name' => 'small gumball', 'filling'

=> 'solid', 'price' => 0.04);

Use array_keys() to get an array of an array's keys

$prodKeys = array_keys($product);

Use array_values() to get an array of an array's values

$prodValues = array_values($product);

When would you want to use either of these?

ITM 352 9

Removing and Inserting Elements$product = array('small gumball','solid', 0.04);

Usually you will simply create a new array if you need to insert or remove elements

$prodNoFilling = array($product[0], $product[2]);

You can use array_splice() to insert or remove elements directly

array_splice($product, 1, 1); // removes elem 1array_splice($product, 1, 1, 'hollow'); // replaces elem 1array_splice($product, 1, 0, 'logo'); // inserts at elem

1

Challenge: What happens to $product if you executed the above as is?

ITM 352 10

Vector Functions$nums1 = array(1,2,3,4,5, 5.0);$nums2 = array(5,6,7,8,9); Merging arrays – splices together$mergeNums = array_merge($nums1, $nums2); Array Unique – all unique values (uses ==)$unionNums = array_unique($nums1); Array Intersection – all common values (uses ==)$intsctNums = array_intersect($nums1, $nums2); Array Difference – return all values of $nums1 that are

not in $nums2$diffNums = array_diff($nums1, $nums2);

Do Lab #5