We must have heard about object-oriented programming in C++ and Java; similarly, PHP also supports Object-Oriented Programming (OOP), where we deal with classes and objects to create a program. Here classes are the data structures, and objects are the blueprints that represent these data structures. This tutorial briefly explains PHP Object-Oriented Programming terminology with an example.
PHP OOP Terminology
Before going into detail about PHP OOP, it is necessary to know its essential terms:
| Keyword | Description |
|---|---|
| Class |
|
| Object | An object is an instance of a class. |
| Member Variable | Member variables are defined inside the class, and only member functions can access them. |
| MemberFunction | Member functions are operators and functions declared as members of a class and used for accessing object data. |
| Inheritance | Inheritance is a concept where a child class can inherit the functions of a parent class. |
| Parent class | A class is said to be a parent if another class inherits its member functions. It is also called a base class. |
| Child class | A class is said to be a child class if it inherits member functions from another class. It is also called the derived class. |
| Polymorphism | In OOP, Polymorphism means many forms. Generally, polymorphism occurs if there is a hierarchy of classes and the law of inheritance relates to them. |
| Overloading | Overloading can be achieved if some class methods have a similar name but different parameters. |
| Data Abstraction | In data abstraction, some implementation details remain hidden. |
| Encapsulation | Encapsulation is a way to encapsulate all the data and member functions together as one object. |
| Constructor | A constructor is a special function that allows the object’s properties to be initialized automatically upon the creation of the object. |
| Destructor | A destructor is a function that gets called automatically when the object is destroyed, or the script execution is completed or exited. Example |
PHP Class
We can define a class by using the keyword ‘class’ followed by the name of that class:
An Example of a PHP Class:
<?php
/*Example Class*/
class Example
{
/* Member variables */
public $Name, $Age;
/*Constructor method*/
public function __construct($UserName, $UserAge)
{
$this->Name = $UserName;
$this->Age = $UserAge;
}
/*Destructor method*/
public function __destruct(){
echo 'The class "' . __CLASS__ . '" was destroyed!';
}
}
/*Create the class object*/
$Obj1 = new Example("Tom", 22);
$Obj2 = new Example("Dick", 26);
$Obj3 = new Example("Harry", 28);
print_r([$Obj1, $Obj2, $Obj3]);
?>Output:
Array
(
[0] => Example Object
(
[Name] => Tom
[Age] => 22
)
[1] => Example Object
(
[Name] => Dick
[Age] => 26
)
[2] => Example Object
(
[Name] => Harry
[Age] => 28
)
)
The class "Example" was destroyed!
The class "Example" was destroyed!
The class "Example" was destroyed!
The PHP’ $this’ is a reserved keyword that refers to the existing class object.