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What are the commonly used magic methods in php?

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Release： 2023-03-12 17:00:01

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This article mainly introduces relevant information about magic methods commonly used in PHP. Has very good reference value. Let’s take a look at it with the editor

What are the commonly used magic methods in php?

We often use magic methods in PHP, such as construction methods, destructor methods and other magic variables. Let’s summarize some of them below Commonly used magic variables:

construct(),destruct(),clone(),autoload(),tostring(),invoke(),set(),get(),unset (),isset(),call(),callstatic;

##1.constuct()Constructor

Usually after instantiating an object, the properties of the object must be initialized! When instantiating an object, the PHP system will automatically call a method named construct(). We call this method the "constructor method"!

Among them, the constructor can have no parameters!

<?php

class Stu {

 public $stu_name;
 public $stu_age;

//构造方法，实例化时自动调用
 public function construct($name,$age){

  $this->stu_name = $name;
  $this->stu_age = $age;
 } 

}

//实例化stu对象
$stu = new Stu(&#39;孙悟空&#39;,&#39;500&#39;);

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2.destruct() The destructor method

is a pair with the construction method. The construction method is automatically called by the system when an object is "born" , and the destructor method is automatically called by the system when an object "disappears"!

The name of the destructor method is destruct(); note that there cannot be any parameters in it!

<?php

//析构方法
public function destruct(){

}
?>

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Note: The destructor method is called before the object is destroyed!

Function:

The destructor method is generally used to release additional resources occupied by the object. , instead of destroying the object itself!

3.clone() cloning

Trigger timing: It is the work of initializing the new object when cloning an object

//克隆方法在克隆对象的时候对新对象的初始化工作
 
public function clone(){
 
 $this->is_clone=true;
}

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Thinking:

Is the cloned object still an instance of the Student class?

We can use the instanceof operator to make judgments!

instanceof is used to determine whether an object is an instance of a certain class!

Requires two operands, the front is an object variable, and the back is a class name! Return a boolean value!

var_dump($stu instanceof Stu);   　　//返回bool（true）

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4.autoload()Automatic loading of classes

Automatically called when calling a class that does not exist!

<?php 

/**
* 自动加载类
* 需要什么类autoload会自动调用需要的文件
*
*/

public function autoload($class_name)
{
 require_once "../Model/{$class_name}.class.php";
}
 ?>

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5.tostring()

Automatically called when the object is used as a string

6.invoke()

Automatically called when using the object as a function

7, set()

Automatically called when assigning a value to an inaccessible property Calling (for example: calling private properties outside the class)

8.get()

Automatically called when getting inaccessible property values

9.unset()

Automatically called when inaccessible properties are destroyed

10.isset()

Automatically called when determining whether an inaccessible property exists

11.call()

Automatically triggered when an inaccessible ordinary method is called

<?php 
class Stu{

 public function call(){
　　　　echo "error";
 }
}
$stu = new Stu();
//此时Stu类里没有show()方法，会触发call()函数
$stu->show();

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12.callststic()

Automatically triggered when cannot be accessed through static methods

<?php 
class Stu{

 public static function callstatic(){
  echo "error";
 }
}
$stu = new Stu();
//此时Stu类里没有show()方法，会触发call()函数
$stu::show();

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