ITM ITM 352 Array Processing

ITM Simple Array Processing  Arrays 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 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 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 "; Do Lab #2

ITM 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 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 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 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 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 1 array_splice($product, 1, 1, 'hollow'); // replaces elem 1 array_splice($product, 1, 0, 'logo'); // inserts at elem 1 Challenge: What happens to $product if you executed the above as is?

ITM 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