What is the method to destroy objects in PHP

Methods to destroy objects in PHP: 1. Assign NULL to the object variable with the syntax "$obj = null;"; 2. Use the unset() function to destroy the object with the syntax "unset($obj);".

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Destroy objects in PHP Method

Method 1: Assign NULL to the object variable

When the object is not referenced, it will be destroyed, so it can be assigned a value NULL

Example: There is such an object:

<?php
header("Content-type:text/html;charset=utf-8");
class Human {   
  public $name = &#39;张三&#39;;   
  public $gender = null;   
  public function __destruct() {   
      echo &#39;走了!<br />&#39;;   
  }   
}   
$obj = new Human();  
var_dump($obj);
?>

Output result:

Assign NULL to the object variable $obj and destroy the object

$obj = null;
var_dump($obj);

Output result:

Method 2: Use the unset() function to destroy the object

Example 1:

<?php
class Human {   
  public $name = &#39;张三&#39;;   
  public $gender = null;   
  public function __destruct() {   
      echo &#39;走了!<br />&#39;;   
  }   
}   
$a = new Human();   
$b = $c = $d = $a;  
unset($a);    
echo $b->name; //输出张三
echo &#39;<hr />&#39;; //先输出换行线再输出走了    析构函数是在线上触发还是线下触发?
?>

Answer:

$b = $c = $d = $a;By default, the four variables point to the same memory. When unset, the object remains It is used by the other three variables, so the object is not destroyed, so the destructor is triggered offline (the memory is automatically released after the code is executed)

Example 2:

<?php
class Human { 
  public $name = &#39;张三&#39;; 
  public $gender = null; 
   
  public function __destruct() { 
      echo &#39;走了!<br />&#39;; 
  } 
} 
$e = $f = $g = new Human(); 
unset($e); 
unset($f); 
unset($g); 
echo &#39;<hr />&#39;; //同样的问题: 析构函数是在线上触发还是线下触发?
?>

Before the memory is automatically released after the code runs, the object is not referenced by any variable, so the memory is automatically released....The answer is to trigger it online

Recommended learning: "PHP Video Tutorial"

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