oops concepts in php

OOPS OOPS

-Concepts in -Concepts in

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Topics to be covered

What is OOPSClass & ObjectsModifierConstructor DeconstructorClass ConstantsInheritance In PhpMagic FunctionPolymorphism

InterfacesAbstract ClassesStatic Methods And PropertiesAccessor MethodsDetermining A Object's Class

What Is Oop ?

Object Oriented Programming (OOP) is the programming method that involves the use of the data , structure and organize classes of an application. The data structure becomes an objects that includes both functions and data. A relationship between one object and other object is created by the programmer

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Classes

A class is a programmer defined datatype which include local fuctions as well as local data.Like a pattern or a blueprint a oops class has exact specifications. The specification is the class' s contract.

An object is a like a container that contains methods and properties which are require to make a certain data types useful. An object’s methods are what it can do and its properties are what it knows.

Object

Modifier

Modifier

In object oriented programming, some Keywords are private and some are public in class. These keyword are known as modifier. These keywords help you to define how these variables and properties will be accessed by the user of this class.

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Modifier

Private: Properties or methods declared as private are not allowed to be called from outside the class. However any method inside the same class can access them without a problem. In our Emailer class we have all these properties declared as private, so if we execute the following code we will find an error.

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Modifier

<?include_once("class.emailer.php");$emobject = new Emailer("hasin@somewherein.net");$emobject->subject = "Hello world";?>

The above code upon execution gives a fatal error as shown below:

<b>Faprivate property emailer::$subject in <b>C:\OOP with PHP5\Codes\ch1\class.emailer.php</b> on line <b>43</><br />tal error</b>: Cannot access That means you can't access

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Modifier

Public: Any property or method which is not explicitly declared as private or protected is a public method. You can access a public method from inside or outside the class. Protected: This is another modifier which has a special meaning in OOP. If any property or method is declared as protected, you can only access the method from its subclass. To see how a protected method or property actually works, we'll use the following example:

Modifier

To start, let's open class.emailer.php file (the Emailer class) and change the declaration of the $sender variable. Make it as follows:

protected $sender

Now create another file name class.extendedemailer.php with the following code:

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Modifier

<?class ExtendedEmailer extends emailer {function __construct(){} public function setSender($sender) { $this->sender = $sender; }}?>

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Constructor & Destructor

Constructor is Acclimated to Initialize the Object.Arguments can be taken by constructor.A class name has same name as Constructor.Memory allocation is done by Constructor.www.cpd-india.com

Constructor & Destructor

The objects that are created in memory, are destroyed by the destructor.Arguments can be taken by the destructor.Overloading is possible in destructor.It has same name as class name with tiled operator.

ClassContants

Class Constants

You can make constants in your PHP scripts utilizing the predefine keyword to define (constant name, constant value). At the same time to make constants in the class you need to utilize the const keyword. These constants really work like static variables, the main distinction is that they are read-only.

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Class Constants

<?class WordCounter{ const ASC=1; //you need not use $ sign before Constants const DESC=2; private $words; function __construct($filename) { $file_content = file_get_contents($filename); $this->words = (array_count_values(str_word_count(strtolower ($file_content),1)));

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Class Constants

} public function count($order) { if ($order==self::ASC) asort($this->words); else if($order==self::DESC) arsort($this->words);

foreach ($this->words as $key=>$val) echo $key ." = ". $val."<br/>"; }}?>

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Inheritance

Inheritance In Php

Inheritance is a well-known programming rule, and PHP makes utilization of this standard in its object model. This standard will influence the way numerous objects and classes identify with each other. For illustration, when you extend a class, the subclass inherits each public and protected method from the guardian class. Unless a class overrides those techniques, they will hold their unique functionality

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Inheritance

Magic Functions

Magic Functions

There are some predefine function names which you can’t use in your programme unless you have magic functionality relate with them. These functions are known as Magic Functions. Magic functions have special names which begine with two underscores.

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Magic Functions

_ _construct()_ _deconstruct()_ _call()_ _callStatic()_ _get()_ _set()_ _isset()_ _unset()

__sleep()__wakeup()__tostring()__invoke()__ set_state()__ clone()__ debugInfo()

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Magic Functions

_ _construct() Construct function is called when object is

instantiated. Generally it is used in php 5 for creating constructor

_ _deconstruct()It is the opposite of construct function. When object of a class is unset, this function is called.

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Magic Functions

_ _call()When a class in a function is try to call an accessible or inaccessible function , this method is called.

_ _callStatic()It is similar to __callStatic() with only one difference that is its triggered when you try to call an accessible or inaccessible function in static context.

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Magic Functions

_ _get()This function is triggered when your object try call a variable of a class which is either unavailable or inaccessible.

_ _set()This function is called when we try to change to value of a property which is unavailable or inaccessible.

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Polymorphism

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Polymorphism

The ability of a object, variable or function to appear in many form is known as polymorphism. It allows a developer to programme in general rather than programme in specific. There are two types of polymorphism.

compile time polymorphismrun-time polymorphism".

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Interfaces

Interfaces

There are some specific set of variable and functions which can be called outside a class itself. These are known as interfaces. Interfaces are declared using interface keyword.

<?//interface.dbdriver.phpinterface DBDriver{ public function connect(); public function execute($sql);}?>

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Abstract ClassesAbstract Classes

Abstract Classes

A class which is declared using abstract keyword is known as abstract class. An abstract class is not implemented just declared only (followed by semicolon without braces)

<?//abstract.reportgenerator.phpabstract class ReportGenerator{ public function generateReport($resultArray) { //write code to process the multidimensional result array and //generate HTML Report }}? www.cpd-india.com

Static Method And Static Method And PropertiesProperties

Static Methods & Properties

In object oriented programming, static keyword is very crucial. Static properties and method acts as a significant element in design pattern and application design. To access any method or attribute in a class you must create an instance (i.e. using new keyword, like $object = new emailer()), otherwise you can't access them. But there is a difference for static methods and properties. You can access a static method or property directly without creating any instance of that class. A static member is like a global member for that class and all instances of that class

Static Methods & Properties

<?//class.dbmanager.phpclass DBManager{ public static function getMySQLDriver() { //instantiate a new MySQL Driver object and return } public static function getPostgreSQLDriver()

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Static Methods & Properties

{ //instantiate a new PostgreSQL Driver object and

return } public static function getSQLiteDriver() { //instantiate a new MySQL Driver object and return }}?>

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Accessor Accessor MethodMethod

Accessor Method

Accessor methods are simply methods that are solely devoted to get and set the value of any class properties. It's a good practice to access class properties using accessor methods instead of directly setting or getting their value. Though accessor methods are the same as other methods, there are some conventions writing them. There are two types of accessor methods. One is called getter, whose purpose is returning value of any class property. The other is setter that sets a value into a class property. www.cpd-india.com

Accessor Method

<?class Student{private $name;private $roll;More free ebooks : http://fast-file.blogspot.comChapter 2[ 39 ]public function setName($name){$this->name= $name;}

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Accessor Method

public function setRoll($roll){$this->roll =$roll;}public function getName(){return $this->name;}public function getRoll(){return $this->roll;}}?>

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Determining A Object's Class

public function setRoll($roll){$this->roll =$roll;}public function getName(){return $this->name;}public function getRoll(){return $this->roll;}}?>

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