Web Programming Language Week 6 Dr. Ken Cosh PHP Functions & Objects

Recap Introducing PHP Server Side Scripting Variables Flow Control Operators, Conditionals Form Handling

This Week Extending PHP Functions Objects

Why Functions? Less Typing Less Syntax Less Errors Quicker loading time Quicker Execution time Simplify Logic

Existing Functions PHP has hundreds of functions… echo strrev(“.dlrow olleH”); echo str_repeat(“Hip “, 2); echo strtoupper(“hooray!”); echo ucfirst(“ken”); You will gradually pick up more functions as you face more challenges…

Defining Functions function function_name(parameter, parameter) { //Statements }

Returning Values You can return variables return $n1; You can return an array of values return array($n1, $n2, $n3);

Reference Parameters You can prefix a variable with & to make it a reference variable i.e. passes a reference to the value, rather than the variable itself. This allows your function to directly modify the variable’s value. function fix_names(&$n1, &$n2) { $n1 = ucfirst(strtolower($n1)); $n2 = ucfirst(strtolower($n2)); }

Where to function? You could write functions anywhere within your PHP files Overtime you are likely to create a lot of functions, so you could create a file of functions functions.php You can then include that file in your page include “functions.php”;

include & require include will attempt to include another file if the file doesn’t exist it will produce a warning require is the same, except if the file can’t be found it will produce a fatal error require “function.php”

include_once, require_once You may end up with multiple files including multiple other files. If file A includes file B and file C, and file B include file C, you could run into naming problems… include_once and require_once will fix it.

function_exists PHP is continually developed, there are multiple versions. We may need to check if a function exists in our version if(function_exists(“array_combine”)) { …} array_combine() is specific to PHP5 Think! How might needing to do this change between php and javascript?

Objects in PHP We can define classes in PHP class User { public $name, $password; function f1() { //Code Here } Notice, no semicolon!

Objects in PHP We can create instances of our class; $object = new User; $object->name = “Ken”; $object->password = “secret”; print_r($object); Notice, no $

Cloning an Object What would happen here? $object1 = new User; $object1->name = “Ken”; $object2 = $object1; $object2->name = “Jeff”; echo “object 1 name = “. $object1->name. “ ”; echo “object 2 name = “. $object2->name;

Cloning an Object An Alternative $object1 = new User; $object1->name = “Ken”; $object2 = clone $object1; $object2->name = “Jeff”; echo “object 1 name = “. $object1->name. “ ”; echo “object 2 name = “. $object2->name;

Constructors You could use the same name as the class (User), or, you could use __construct() class User { function __construct() { $username = “Guest”; } public $username; }

Destructors We can also have destructor methods; class User { function __destruct() { //Code }

Public, Protected, Private Of course, properties and methods can be public, protected or private in PHP; public – accessible anywhere protected – accessible from within the class, or subclasses private – only accessible from within the class

Inheritance Without wanting to go into details, PHP also supports inheritance class Subscriber extends User { }

Exercise – Calendar Part I Create a form for submitting appointments to a calendar. The form should allow users to input the following information:- Title Date Details Once the user submits the form, the ‘event’ should be displayed on a calendar on a new page.

Exercise - Example FoE Mtg Title 13/12/2011 Date ASEAN-QA meeting, review the handbook first. Detail Submit 2 1

Exercise - Example December Foe Mtg in 1 day(s)

Exercise Example FoE Mtg Title 13/1/2013 Date ASEAN-QA meeting, review the handbook first. Detail Appointment Detail 3