oops characteristics (with examples in php)

OOPS CONCEPTS

Rajishma Trajishmatnair@gmail.comwww.facebook.com/ Rajishma T

Nairtwitter.com/usernamein.linkedin.com/in/profilename9020217968

Disclaimer: This presentation is prepared by trainees of baabtra as a part of mentoring program. This is not official document of baabtra –Mentoring PartnerBaabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt . Ltd

CLASS A class is an expanded concept of a data,it

can hold both data and functions.A class is the blueprint for your object.A class, for example, is like a blueprint for a

house. It defines the shape of the house on paper, with relationships between the different parts of the house clearly defined and planned out, even though the house doesn’t exist.

visibilityThe visibility of class members, (properties,

methods), relates to how that member may be manipulated within, or from outside the class.

private:private members are accessible only in the class itself.

Public:public members are accessible outside the class(anywhere).

Protected:protected members are accessible in the same package,and the subclasses of the class and inside the class.

OOPS CHARACTERESTICS

data encapsulation. inheritance.Polymorphism.Data abstraction.

ENCAPSULATION

The wrapping up of a data and functions into a single unit(which is called class).

Encapsulation means that some or all of an objects internal structure is hidden from the outside world.

Hidden information may only be accessed through the object’s public interface.

example<?phpclass MyClass{ public $prop1 = "I'm a class property!";

public function setProperty($newval) { $this->prop1 = $newval; } public function getProperty() { return $this->prop1 . "<br />"; }}$obj = new MyClass;echo $obj->getProperty(); // Get the property value$obj->setProperty("I'm a new property value!"); // Set a new oneecho $obj->getProperty(); // Read it out again to show the change?>Output• http://localhost/phpWorkspace/oops.php/class.php

INHERITANCE• When you want to create a new class and there

is already a class that includes some of the code that you want, you can derive your new class from the existing class.

• A class that is derived from another class is called a subclass (also a derived class, extended class, or child class).

• The class from which the subclass is derived is called a superclass (also a base class or a parent class).

TYPES OF INHERITANCE

• Single Inheritance • Hierarchical Inheritance • Multi Level Inheritance • Hybrid Inheritance • Multiple Inheritance

SINGLE INHERITANCE

• when a single derived class is created from a single base class then the inheritance is called as single inheritance.

HIERARCHICAL INHERITANCE

• when more than one derived class are created from a single base class, then that inheritance is called as hierarchical inheritance.

MULTILEVEL INHERITANCE

• when a derived class is created from another derived class, then that inheritance is called as multi level inheritance.

HYBRID INHERITANCE

• Any combination of single, hierarchical and multi level inheritances is called as hybrid inheritance.

MULTIPLE INHERITANCE

• when a derived class is created from more than one base class then that inheritance is called as multiple inheritance.

Single inheritance<?phpclass parentclass { public function sum($a,$b) { echo $a+$b; }}class childclass extends parentclass{ public function diff($a,$b) { echo $a-$b; }}$obj1=new childclass();$obj1->sum(4,5);echo "<br />";echo "<br />";$obj1->diff(8,3);?>Output:http://localhost/phpWorkspace/oops.php/inheritance1.php

Hierarchical inheritance<?phpclass a{ public function function_a() { echo "classA"; }}class b extends a{ public function function_b() { echo "classB"; }}class c extends a{ public function function_c() { echo "classC";}}

echo c::function_c();echo "<br />";echo c::function_a();echo “<br />echo b::function_a();

?>

• Output

http://localhost/phpWorkspace/oops.php/hierarchicalinheritance.php

Multilevel inheritance

<?phpclass a{ public function function_a(){ echo 'classa';}}class b extends a{public function function_b(){echo 'classb';}}class c extends b{public function function_c(){echo 'classc';}}

echo c::function_c();echo "<br />";eCho c::function_b();echo "<br />";echo c::function_a();

?>OUTPUT

http://localhost/phpWorkspace/oops.php/multilevel.php

POLYMORPHISM

• Poly means many,morphism means forms.• Polymorphism feature enables classes to

provide different implementation of methods having the same name.

• Two types of polymorphismCompile time(overloading)Runtime(overriding)

OVERRIDING• When we create a function in a derived class

with the same signature (in other words a function has the same name, the same number of arguments and the same type of arguments) as a function in its parent class then it is called method overriding.

example

<?phpclass Shap{ function draw(){}} class Circle extends Shap{ function draw() { print "Circle has been drawn.</br>"; }}class Triangle extends Shap{ function draw() { print "Triangle has been drawn.</br>"; }}class Ellipse extends Shap{ function draw() { print "Ellipse has been drawn."; }}

}

$Val=array(2);$Val[0]=new Circle();$Val[1]=new Triangle();$Val[2]=new Ellipse();for($i=0;$i<3;$i++) { $Val[$i]->draw();}?>

• Outputhttp://localhost/phpWorkspace/oops.php/overriding.php

OVERLOADING

• Method overloading means having two or more methods with the same name but different signatures in the same scope. These two methods may exist in the same class or another one in base class and another in derived class.

Example<?phpfunction findSum() { $sum = 0; foreach (func_get_args() as $arg) { $sum += $arg; } return $sum;}echo findSum(1, 2), '<br />'; echo findSum(10, 2, 100), '<br />'; echo findSum(10, 22, 0.5, 0.75, 12.50), '<br />'; ?>Output:http://localhost/phpWorkspace/oops.php/overloading.php

DATA ABSTRACTION

• Any representation of data in which the implementation details are hidden (abstracted).

• Data abstraction refers to, providing only essential information to the outside word and hiding their background details ie. to represent the needed information in program without presenting the details

• They provide sufficient public methods to the outside world to play with the functionality of the object and to manipulate object data ie. state without actually knowing how class has

been implemented internally.

ABSTRACT CLASS

• An abstract class is one that cannot be instantiated, only inherited. You declare an abstract class with the keyword abstract

• When inheriting from an abstract class, all methods marked abstract in the parent's class declaration must be defined by the child;

<?phpabstract class One{abstract function disp();}class Two extends One {public function disp() {echo "Inside the child class<br/>";}}class Three extends One{public function disp(){echo "Inside the child class 2<br/>";}}

$two=new Two();echo "<b>Calling from the child class Two:</b><br/>";$two->disp();echo "<b>Calling from the child class Three:</b><br/>";$three=new Three();$three->disp();?>Output

http://localhost/phpWorkspace/oops.php/abstractclass.php

INTERFACE

• Interface is a special class used like a template for a group of classes with similar functions, which must define a certain structure of methods.

• It can contain constants and method declarations, but not method bodies.

<?php interface testdrive { function drive(); function stop(); }class vehicle implements testdrive{ public function __construct() { echo 'About this Vehicle.<br />'; } public function drive() { echo 'VRRROOOOOOM!!!'; }

public function stop() { echo 'SSSCCRRREEEEEECCHH!!!<br />'; }}

$object = new vehicle;$object->drive();$object->stop();?>

Outputhttp://localhost/phpWorkspace/oops.php/interface.php

ABSTRACT CLASS INTERFACE

The Abstract methods can declare with Access modifiers like public, internal, protected. When implementing in subclass these methods must be defined with the same (or a less restricted) visibility.

All methods declared in an interface must be public.

Abstract class can contain variables and concrete methods.

Interfaces cannot contain variables and concrete methods except constants.

A class can Inherit only one Abstract class and Multiple inheritance is not possible for Abstract class.

A class can implement many interfaces and Multiple interface inheritance is possible.

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If this presentation helped you, please visit our page facebook.com/baabtra and like it.

Thanks in advance.

www.baabtra.com | www.massbaab.com |www.baabte.com