This document provides an introduction to object-oriented programming concepts in PHP including defining classes, creating objects, using methods and properties, inheritance, and the differences between OOP in PHP4 and PHP5. Classes define objects with attributes and behaviors, objects are instantiated from classes and can access methods and properties, and child classes inherit attributes and behaviors from parent classes.

1. PHP Classes and Object Orientation

2. Revision HIstory # Version Date Rationale for change Change Description 1 1.0 26-Feb-2008 Initial Version 2

3. Revision HIstory Document Name Training Material Document Code QMS-TEM-OT 08 Version 1.0 Date 26-Feb-2008 Created By Ms. Padmavathy Reviewed BY SPG Approved By Mr. Vijay

6. Conceptually, what does a function represent? … give the function something (arguments), it does something with them, and then returns a result… Action or Method

7. What is a class ? Conceptually, a class represents an object , with associated methods and variables

8. Class Definition <?php class dog { public $name; public function bark() { echo ‘Woof!’ ; } } ?> An example class definition for a dog. The dog object has a single attribute, the name, and can perform the action of barking.

9. Class Definition <?php class dog { public $name; public function bark() { echo ‘Woof!’ ; } } ?> class dog { Define the name of the class.

10. Class Definition <?php class dog { public $name; public function bark() { echo ‘Woof!’ ; } } ?> public $name; Define an object attribute (variable), the dog’s name.

11. Class Definition <?php class dog { public $name; public function bark() { echo ‘Woof!’ ; } } ?> public function bark() { echo ‘Woof!’ ; } Define an object action (function), the dog’s bark.

12. Class Defintion Similar to defining a function.. The definition does not do anything by itself . It is a blueprint, or description, of an object. To do something, you need to use the class…

13. Class Usage <?php require ( ‘dog.class.php’ ); $puppy = new dog(); $puppy->name = ‘Rover’ ; echo “ {$puppy->name} says ” ; $puppy->bark(); ?>

14. Class Usage <?php require ( ‘dog.class.php’ ); $puppy = new dog(); $puppy->name = ‘Rover’ ; echo “ {$puppy->name} says ” ; $puppy->bark(); ?> require ( ‘dog.class.php’ ); Include the class definition

15. Class Usage <?php require ( ‘dog.class.php’ ); $puppy = new dog(); $puppy->name = ‘Rover’ ; echo “ {$puppy->name} says ” ; $puppy->bark(); ?> $puppy = new dog(); Create a new instance of the class.

16. Class Usage <?php require ( ‘dog.class.php’ ); $puppy = new dog(); $puppy->name = ‘Rover’ ; echo “ {$puppy->name} says ” ; $puppy->bark(); ?> $puppy->name = ‘Rover’ ; Set the name variable of this instance to ‘Rover’.

17. Class Usage <?php require ( ‘dog.class.php’ ); $puppy = new dog(); $puppy->name = ‘Rover’ ; echo “ {$puppy->name} says ” ; $puppy->bark(); ?> echo “ {$puppy->name} says ” ; Use the name variable of this instance in an echo statement..

18. Class Usage <?php require ( ‘dog.class.php’ ); $puppy = new dog(); $puppy->name = ‘Rover’ ; echo “ {$puppy->name} says ” ; $puppy->bark(); ?> $puppy->bark(); Use the dog object bark method.

19. One dollar and one only… $puppy->name = ‘Rover’ ; The most common mistake is to use more than one dollar sign when accessing variables. The following means something entirely different.. $puppy->$name = ‘Rover’ ;

22. Constructor Example <?php class dog { public $name; public function __construct ($nametext) { $this->name = $nametext; } public function bark() { echo ‘Woof!’; } } ?>

23. Constructor Example <?php … $puppy = new dog( ‘Rover’ ); … ?> Constructor arguments are passed during the instantiation of the object.

27. Inheritance example The American Kennel Club (AKC) recognizes three sizes of poodle - Standard, Miniature, and Toy … class poodle extends dog { public $type; public function set_type($height) { if ($height<10) { $this->type = ‘Toy’ ; } elseif ($height>15) { $this->type = ‘Standard’ ; } else { $this->type = ‘Miniature’ ; } } }

28. Inheritance example The American Kennel Club (AKC) recognizes three sizes of poodle - Standard, Miniature, and Toy… class poodle extends dog { public $type; public function set_type($height) { if ($height<10) { $this->type = ‘Toy’ ; } elseif ($height>15) { $this->type = ‘Standard’ ; } else { $this->type = ‘Miniature’ ; } } } class poodle extends dog { Note the use of the extends keyword to indicate that the poodle class is a child of the dog class…

29. Inheritance example … $puppy = new poodle( ‘Oscar’ ); $puppy->set_type(12); // 12 inches high! echo “Poodle is called {$puppy->name} , ” ; echo “of type {$puppy->type} , saying “ ; echo $puppy->bark(); …

35. Thank you