What is Constructor and Destructor?

 Constructor:

Constructor is a special type of function which will be called automatically whenever there is any object created from a class.

//Old (PHP4) class myClass{ function myClass(){ // Define logic in constructor } }

//New (PHP5+) class myClass{ function __construct(){ // Define logic in constructor } }

Note- Old style constructors are DEPRECATED in PHP 7.0, and will be removed in a future version. You should always use __construct() in new code.

Destructor:

Destructor is a special type of function which will be called automatically whenever any object is deleted or goes out of scope.

class myClass{ function __construct(){ // Define logic in constructor } function __destruct(){ // this is destructor } }

Types of constructors:

1. Default constructor

A constructor without any parameters is called a default constructor.

2. Parameterized constructor

A constructor with at least one parameter is called a parametrized constructor.

class Person{ public $name; public $address; public function __construct($name){ // parameterized constructor with name argument $this->name = $name; } } $perObj1 = new Person("Full Stack Tutorials"); // parameterized constructor with name argument echo $perObj1->name; //Output: Full Stack Tutorials
3. Copy Constructor
class Person{ public $name; public $address; public function __construct($name){ // parameterized constructor with name argument $this->name = $name; } public function __clone(){ } } $perObj1 = new Person("Full Stack Tutorials"); // parameterized constructor with name argument $perObj2 = clone $perObj1; // copy constructor initialize $perObj2 with the values of $perObj1 echo $perObj2->name; //Output: Full Stack Tutorials
4. Static Constructor
5. Private Constructor

Purpose of Private Constructor: It ensures that there can be only one instance of a Class and provides a global access point to that instance and this is common with The Singleton Pattern.

class myClass { private static $instance; private function __construct() { } public static function get_instance() { if (!self::$instance) self::$instance = new myClass(); return self::$instance; } }