A recursive function is a function that calls itself. If the function keeps calling itself, how does it know when to stop? You set up a condition.
<?php
class Recursion{
function recursive($num){
echo $num,"<br/>";
if(isset($num) && $num < 10){
return $this->recursive($num + 1);
}
}
}
$obj = new Recursion;
$obj->recursive(1);
Basically multiple inheritance does not supported by PHP. One class can only extend or inherit from one other class. But there are many cases when you want to extend more than one classes for code reusability. To overcome this problem, as of version 5.4, PHP introduced a new feature of code reuse named trait.
So what are Traits?. Traits are a mechanism for code reuse. A Trait is simply a group of methods that you want include within another class. A Trait, like an abstract class, but It is not allowed to instantiate a trait on its own.
/* mobile.php */
<?php
class Mobile{
function model(){
echo "Samsung Galexy 5 <br/>";
}
}
/* charger.php */
<?php
trait Charger{
function battery(){
echo "2500 MP Battery <br/>";
}
function power(){
echo "Power of Battery </br>";
}
}
/* projector.php */
<?php
trait Projector{
function range(){
echo "Projector range 5 meter <br>";
}
function power(){
echo "Power of range <br/>";
}
}
/* body.php */
<?php
trait Body{
function display(){
echo "Display 5.5 inc <br/>";
}
public $name = "Smart Phone";
abstract function tabu();
}
/* glass.php */
<?php
include_once('body.php');
trait Glass{
use Body;
/*function display(){
echo "Cornic Gorila Glass <br>";
}*/
}
/* index.php */
<?php
include_once('mobile.php');
include_once('charger.php');
include_once('projector.php');
include_once('glass.php');
class Samsung extends Mobile{
use Charger,Projector,Glass{
Charger::power insteadof Projector;
Projector::power as Ppower;
}
/*function display(){
echo "This is from index";
}*/
function tabu(){
}
}
$obj = new Samsung;
$obj->model();
$obj->battery();
$obj->range();
$obj->power();
$obj->Ppower();
$obj->display();
echo $obj->name;
Normally PHP does not allowed to use same multiple class name or method. So what you do on that situation. You can use Namespace. Namespace just like a virtual directory. You can use same multiple class name or method without a name collision.
/* first.php */
<?php
class A{
function __construct(){
echo "I am at global space </br>";
}
}
/* second.php */
<?php
namespace second;
class A{
function __construct(){
echo "I am at second space <br/>";
}
}
/* index.php */
<?php
include "first.php";
include "second.php";
use second\A;
//$obj = new second\A; // qualified class name
$obj = new A; // unqualified class name
$obj = new \A; // fully qualified class name
The self keyword does not follow the same rules of inheritance. self always resolves to the class in which it is used. This means that if you make a method in a parent class and call it from a child class, self will not reference the child as you might expect.
<?php
class Php{
public static function framework(){
echo static::getClass()."<br/>";
}
public static function getClass(){
return __CLASS__;
}
}
class ChildPhp extends Php{
public static function getClass(){
return __CLASS__;
}
}
$php = new php;
$php->framework();
$childphp = new ChildPhp;
$childphp->framework();
A constant is declared with the const keyword followed by a name (is not prefixed with a dollar sign like properties).
Syntax: const CONSTANT_NAME
The main difference between properties and constants is that the constant value cannot be changed once it is set.
<?php
/**
* Area = π r2
*/
// Procedural way constant define
// define("CONSTANT_NAME", 'value');
class Circle {
const PI = 3.1415;
public function area($radius){
return $radius * $radius * self::PI;
}
}
$circle = new Circle;
echo $circle->area(5);
Static properties and methods in php can directly accessible without creating object of class. You can declare static property and method using static keyword.
<?php
class User{
public static $name;
static function getName(){
self::$name = "Ataur Rahman";
}
}
User::getName();
echo User::$name;
It allows you to create a new class that reuses the properties and methods from an existing class. A class that inherits from another class is called subclass (also a child class).
<?php
class Fruits{
public $name;
public function setName($name){
$this->name = $name;
}
}
class Apple extends Fruits{
function juice(){
echo "Juice <br/>";
}
}
class Mango extends Fruits{
}
$apple = new Apple();
$apple->juice();
$apple->setName("My Apple");
echo $apple->name;
echo "<br/>";
$mango = new Mango();
$mango->setName("My Mango");
echo $mango->name;
You can specify what type of data expected in a function declaration. It could be Array type, int type, object type data.
<?php
class Book{
public $price;
public $authors;
function getPrice(int $price){
$this->price = $price;
}
function Authors(array $name){
$this->authors = $name;
}
}
$book = new Book;
$book->getPrice(100);
echo $book->price;
echo "<br/>";
$book->Authors(['Araf','Jahir']);
print_r($book->authors);
An abstract class cannot be instantiated. In other words, it is not allowed to create a new instance of an abstract class. An abstract class can contain properties and methods.
<?php
abstract class Student{
public $name;
public $age;
public function details(){
return "My name is ".$this->name.". I am ".$this->age." years old <br/>";
}
abstract public function book();
}
class Boy extends Student{
function describe(){
return parent::details()." and I am a college student <br/>";
}
public function book(){
return "I like to read story book";
}
}
$boy = new Boy;
$boy->name = "Faruk";
$boy->age = 18;
echo $boy->describe();
echo $boy->book();
An interface consists of methods that contain no implementation. In other words, all methods of the interface are abstract methods. A class can only inherit from one class whereas a class can implement one or more interfaces.All the methods in the interface must have public visibility level
<?php
interface Java{
public function JavaCoder();
}
interface Php{
public function PhpCoder();
}
interface Python{
public function PythonCoder();
}
class Programmer implements Java,Php,Python{
function __construct(){
$this->JavaCoder();
$this->PhpCoder();
$this->PythonCoder();
}
function JavaCoder(){
echo "I am a Java Coder <br/>";
}
function PhpCoder(){
echo "I am a Php Coder <br/>";
}
function PythonCoder(){
echo "I am a Python Coder";
}
}
new Programmer();
