PHP is a server side scripting language, mainly used for web development but also used as a general purpose programming language. Object Oriented Programming (PHP OOP), is a type of programming language principle added to php5, which helps in building complex and reusable web applications.<\/p>\n\n\n\n
Object Oriented concepts in PHP are:<\/p>\n\n\n\n
Classes & Objects:<\/p>\n\n\n\n
A class is a programmer-defined data type, which includes local methods and local variables. This is a collection of objects. Objects have properties and behaviors.<\/p>\n\n\n\n
First we have to define the php class, where the class name must be the same as the file name.<\/p>\n\n\n\n
Example for a simple class:<\/p>\n\n\n\n
<?php<\/p>\n\n\n\n
class Books{<\/p>\n\n\n\n
public function name(){<\/p>\n\n\n\n
echo “Drupal book”;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
public function price(){<\/p>\n\n\n\n
echo “900 Rs\/-“;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
}<\/p>\n\n\n\n
\/\/To create php object we have to use a new operator. Here php object is the object of the Books Class.<\/p>\n\n\n\n
$obj = new Books();<\/p>\n\n\n\n
$obj->name();<\/p>\n\n\n\n
$obj->price();<\/p>\n\n\n\n
?><\/p>\n\n\n\n
Output:<\/p>\n\n\n\n
Drupal book<\/p>\n\n\n\n
900 Rs\/-<\/p>\n\n\n\n
Creating Objects in PHP<\/p>\n\n\n\n
When a class is created, we can create any number of objects to that class. The object is created with the help of the new keyword.<\/p>\n\n\n\n
Call Member Function<\/p>\n\n\n\n
When object is created we can access variables and functions of class methods with the help of ‘-> operator, accessing methods is done to get information from that method. Also see how we can access object properties via variables<\/p>\n\n\n\n
<?php<\/p>\n\n\n\n
class Mobile {<\/p>\n\n\n\n
\/* Member variables *\/<\/p>\n\n\n\n
var $price;<\/p>\n\n\n\n
var $title;<\/p>\n\n\n\n
\/* Member functions *\/<\/p>\n\n\n\n
function setPrice($par){<\/p>\n\n\n\n
$this->price = $par;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
function getPrice(){<\/p>\n\n\n\n
echo $this->price .”<\/p>\n\n\n\n
“;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
function setName($par){<\/p>\n\n\n\n
$this->title = $par;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
function getName(){<\/p>\n\n\n\n
echo $this->title .”<\/p>\n\n\n\n
“;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
}<\/p>\n\n\n\n
$Samsung = new Mobile();<\/p>\n\n\n\n
$Xiaomi = new Mobile();<\/p>\n\n\n\n
$Iphone = new Mobile();<\/p>\n\n\n\n
$Samsung->setName( “SamsungS8 );<\/p>\n\n\n\n
$Iphone->setName( “Iphone7s” );<\/p>\n\n\n\n
$Xiaomi->setName( “MI4” );<\/p>\n\n\n\n
$Samsung->setPrice( 90000 );<\/p>\n\n\n\n
$Iphone->setPrice( 65000 );<\/p>\n\n\n\n
$Xiaomi->setPrice( 15000 );<\/p>\n\n\n\n
Now you call another member functions to get the values set by in above example<\/p>\n\n\n\n
$Samsung->getName();<\/p>\n\n\n\n
$Iphone->getName();<\/p>\n\n\n\n
$Xiaomi->getName();<\/p>\n\n\n\n
$Samsung->getPrice();<\/p>\n\n\n\n
$Iphone->getPrice();<\/p>\n\n\n\n
$Xiaomi->getPrice();<\/p>\n\n\n\n
?><\/p>\n\n\n\n
Output<\/p>\n\n\n\n
Samsung S8<\/p>\n\n\n\n
Iphone S7<\/p>\n\n\n\n
MI4<\/p>\n\n\n\n
90000<\/p>\n\n\n\n
65000<\/p>\n\n\n\n
15000<\/p>\n\n\n\n
Legacy<\/p>\n\n\n\n
When the properties and methods of a parent class are accessed by a child class, we call the concept of having inheritance. Child classes can inherit parent methods and provide their own method implementation, this property is called overridden method. When the same method of the parent class is inherited, we call the inherited method. Now let’s take a look at the inheritance types supported in Object Oriented Programming and the corresponding Php inheritance examples.<\/p>\n\n\n\n
Inheritance Type<\/p>\n\n\n\n
Single Tier Inheritance:<\/p>\n\n\n\n
In Single Level Inheritance Parent class method will be extended by child class. All methods can be inherited.<\/p>\n\n\n\n
Single Tier Inheritance Example<\/p>\n\n\n\n
<?php<\/p>\n\n\n\n
class A {<\/p>\n\n\n\n
public function printItem($string) {<\/p>\n\n\n\n
echo ‘Hi : ‘ . $string . “\\n;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
public function printPHP() {<\/p>\n\n\n\n
echo ‘I am from valuebound’ . PHP_EOL;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
}<\/p>\n\n\n\n
class B extends A {<\/p>\n\n\n\n
public function printItem($string) {<\/p>\n\n\n\n
echo ‘Hi: ‘ . $string . PHP_EOL;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
public function printPHP() {<\/p>\n\n\n\n
echo “I am from ABC”;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
}<\/p>\n\n\n\n
$a = new A();<\/p>\n\n\n\n
$b = new B();<\/p>\n\n\n\n
$a->printItem(‘Raju’);<\/p>\n\n\n\n
$a->printPHP(); <\/p>\n\n\n\n
$b->printItem(‘savan’);<\/p>\n\n\n\n
$b->printPHP(); <\/p>\n\n\n\n
?><\/p>\n\n\n\n
Output<\/p>\n\n\n\n
Hi : Pavan I am from valuebound Hi: savan I am from ABC<\/p>\n\n\n\n
Graded Inheritance:<\/p>\n\n\n\n
In MultiLevel Inheritance, parent class methods will be inherited by child class and subclass will inherit child class methods.<\/p>\n\n\n\n
<?php<\/p>\n\n\n\n
class A {<\/p>\n\n\n\n
public function myage() {<\/p>\n\n\n\n
return “age is 80\\n”;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
}<\/p>\n\n\n\n
class B extends A {<\/p>\n\n\n\n
public function mysonage() {<\/p>\n\n\n\n
return “age is 50\\n”;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
}<\/p>\n\n\n\n
class C extends B {<\/p>\n\n\n\n
public function mygrandsonage() {<\/p>\n\n\n\n
return “age is 20\\n”;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
public function myHistory() {<\/p>\n\n\n\n
echo “Class A ” .$this->myage();<\/p>\n\n\n\n
echo “Class B “.$this-> mysonage();<\/p>\n\n\n\n
echo “Class C ” . $this->mygrandsonage();<\/p>\n\n\n\n
}<\/p>\n\n\n\n
}<\/p>\n\n\n\n
$obj = new C();<\/p>\n\n\n\n
$obj->myHistory();<\/p>\n\n\n\n
?><\/p>\n\n\n\n
Output<\/p>\n\n\n\n
Class A age is 80<\/p>\n\n\n\n
Class B age is 50<\/p>\n\n\n\n
Class C age is 20<\/p>\n\r\n