PHP Class and Objects

Class and objects is a programming template to write a program in a block.

It is helps to developer write complex program in simple way, reuse a program in multiple applications and create a structural program.

A class has two member one Variables and two Functions. A class is a program structure where developer defines application logic.

Object is a way which use to access class. Create an object developer access their application logic which defines in a class anywhere in a project.

Class and Object is a very useful and easy way to create a complicated application in a simple way.

Creating Class:

<?php
class Pen{
	var $name = “Ink”;
	var $price  = 25;
    function describe(){
	   echo “I am a pen Class”;
    }
}
?>

<?php

class Pen{

var $name = “Ink”;

var $price = 25;

function describe(){

echo “I am a pen Class”;

}

Explanation:

Create a class with “class” keyword then define a class name. The name must start with string or underscore (_).

PHP is a case sensitive language so class name also case sensitive. Means Pen is write word to access this class. start PEN, pEn, The name not the same.

Between { } define whole logic or code. Variable must be declared with var keyword or public keyword and all logic operation must be defined in function.

Creating Object

<?php
class Pen{
	var $name = “Ink”;
	var $price  = 25;
 function describe(){
	echo “I am a pen Class”;
}
}
$obj = new Pen;
echo gettype($obj); //gettype() return the data-type of a variable 
?>

<?php

class Pen{

var $name = “Ink”;

var $price = 25;

function describe(){

echo “I am a pen Class”;

}

$obj = new Pen;

echo gettype($obj); //gettype() return the data-type of a variable

Explanation:

new keyword create object of a class. Object has authority to access the class variable and function out of the class.

In this example $obj is an object of Pen class, $obj can access $name, $price or can call the describe() function out of the class.

Object never creates within class.

Accessing Members and Functions

<?php
class Fruit{
     var $name = “Banana”;
     var $price  = 200;
     function describe(){
              echo “The bucket is full of”.$this->name.” and price of this bucket is ”.$this->price;
        }
}

$obj = new Fruit;
$obj->describe();
echo “<br>”;
echo $obj->name;
echo “<br>”;
echo $obj->price;
?>

<?php

class Fruit{

var $name = “Banana”;

var $price = 200;

function describe(){

echo “The bucket is full of”.$this->name.” and price of this bucket is ”.$this->price;

}

$obj = new Fruit;

$obj->describe();

echo “<br>”;

echo $obj->name;

echo “<br>”;

echo $obj->price;

Output:

The bucket is full of Banana and price of this bucket is 200
Banana
200

The bucket is full of Banana and price of this bucket is 200

Banana

200

Explain:

Accessing class member variable and function by object. “->” this is accessing symbol.

$this variable is use to access class member variable in to the class member function. $this is object pointer, with reference an instance of class.