PHP : Constructors and Destructors :: คู่มือ php การใช้ ฟังก์ชั่น

Forgot Password ??

PHP , ASP , ASP.NET, VB.NET, C#, Java , jQuery , Android , iOS , Windows Phone

	Registered : 109,037

HOME > PHP Manual > Constructors and Destructors

ลองใช้ค้นหาข้อมูล

Autoloading Objects

Visibility

Classes and Objects (PHP 5)

PHP Manual

Constructors and Destructors

Constructor

void __construct ([ mixed $args [, $... ]] )

PHP 5 allows developers to declare constructor methods for classes. Classes which have a constructor method call this method on each newly-created object, so it is suitable for any initialization that the object may need before it is used.

Note: Parent constructors are not called implicitly if the child class defines a constructor. In order to run a parent constructor, a call to parent::__construct() within the child constructor is required.

Example #1 using new unified constructors


<?php
class BaseClass {
   function __construct() {
       print "In BaseClass constructor\n";
   }
}

class SubClass extends BaseClass {
   function __construct() {
       parent::__construct();
       print "In SubClass constructor\n";
   }
}

$obj = new BaseClass();
$obj = new SubClass();
?>

For backwards compatibility, if PHP 5 cannot find a __construct() function for a given class, it will search for the old-style constructor function, by the name of the class. Effectively, it means that the only case that would have compatibility issues is if the class had a method named __construct() which was used for different semantics.

Destructor

void __destruct ( void )

PHP 5 introduces a destructor concept similar to that of other object-oriented languages, such as C++. The destructor method will be called as soon as all references to a particular object are removed or when the object is explicitly destroyed or in any order in shutdown sequence.

Example #2 Destructor Example


<?php
class MyDestructableClass {
   function __construct() {
       print "In constructor\n";
       $this->name = "MyDestructableClass";
   }

   function __destruct() {
       print "Destroying " . $this->name . "\n";
   }
}

$obj = new MyDestructableClass();
?>

Like constructors, parent destructors will not be called implicitly by the engine. In order to run a parent destructor, one would have to explicitly call parent::__destruct() in the destructor body.

Note: Destructors called during the script shutdown have HTTP headers already sent. The working directory in the script shutdown phase can be different with some SAPIs (e.g. Apache).

Note: Attempting to throw an exception from a destructor (called in the time of script termination) causes a fatal error.

Autoloading Objects

Visibility

Classes and Objects (PHP 5)

PHP Manual

สอน Windows Phone การเขียนโปรแกรม Windows Phone 7 และ 8

สอน Java GUI การเขียนโปรแกรม ภาษา Java GUI

Free Tutorial

	สอน Google Maps Api
	สอน Windows Service
	สอน Entity Framework
	สอน Android
	สอน Java เขียน Java
	Java GUI Swing
	สอน JSP (Web App)
	iOS (iPhone,iPad)
	Windows Phone
	Windows Azure
	Windows Store
	Laravel Framework
	Yii PHP Framework
	สอน jQuery
	สอน jQuery กับ Ajax
	สอน PHP OOP (Vdo)
	Ajax Tutorials
	SQL Tutorials
	สอน SQL (Part 2)
	JavaScript Tutorial
	Javascript Tips
	VBScript Tutorial
	VBScript Validation
	Microsoft Access
	MySQL Tutorials
	-- Stored Procedure
	MariaDB Database
	SQL Server Tutorial
	SQL Server 2005
	SQL Server 2008
	SQL Server 2012
	-- Stored Procedure
	Oracle Database
	-- Stored Procedure
	SVN (Subversion)
	แนวทางการทำ SEO
	ปรับแต่งเว็บให้โหลดเร็ว