PHP classes and objects_PHP tutorial

PHP classes and objects

The object model has been completely rewritten since PHP 5 for better performance and more features. This is the biggest change since PHP 4. PHP 5 has a complete object model.​

New features in PHP 5 include access control, abstract and final classes and methods, additional magic methods, interfaces, object copying and type constraints.

PHP treats objects in the same way as references and handles, that is, each variable holds a reference to the object rather than a copy of the entire object.

Attributes:

Variable members of a class are called attributes

Attribute declaration keywords can be public protected private

Variables in attributes can be initialized, but the initialization must be a constant and not a calculation formula

For example

private $name="tom"; //ok

private $name="tom"."jack"; //error

Constant in class:

The value of a constant must be a fixed value and cannot be a variable, class attribute, mathematical operator, function call, etc.

Only const NAME='tom'; can be used to define constants

Access constants use self::NAME inside the class and classname: NAME outside the class

Auto-loading classes:

Case List:

index.php文件
<?php
header("content-type:text/html;charset=utf-8");
function __autoload($className){
require_once $className.&#39;.php&#39;;
}
$obj = new Name();
$obj2 = new User();
var_dump($obj->getName());

Name.php文件
<?php
header("content-type:text/html;charset=utf-8");
class Name{
function getName(){
return "欧阳俊";
}
}

User.php文件
<?php
header("content-type:text/html;charset=utf-8");
class User{
function getUser(){
return array(&#39;ouyangjun&#39;,&#39;jpp&#39;);
}
}

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