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In PHP, constructors and destructors are used in classes. Now I will give you a detailed introduction to the method of using constructors and destructors in PHP classes. Friends who need to know more can refer to it. .
Destructor
The role of the PHP destructor is just the opposite of the constructor. The constructor is automatically executed when the object is instantiated, while the destructor is automatically executed when the object is destroyed.
By default, PHP only releases the memory occupied by object properties and does not destroy object-related resources. Instead, it uses the destructor to execute code after using an object to clear the memory and destroy the object from memory. The structure of the destructor function __destruct() is as follows:
代码如下 | 复制代码 |
function __destruct(){ /* class initialization code */ } |
The destructor is automatically called by the system and cannot take parameters.
Example:
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function __destruct(){ echo "Run ends, execute destructor"; } } $p=new des(); /* Instantiate class */ $sum=0; for($i=0;$i<10;$i++){ $sum=$sum+$i; echo $sum ." "; } ?>
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How to call the destructor in PHP? The destructor is called when the php script is no longer associated with the object. If you want to explicitly destroy an object by calling the destructor, you can assign no value to the variable pointing to the object. You usually assign the variable to NULL or use the unset() function.
Example:
代码如下 | 复制代码 |
class des{ |
The code is as follows | Copy code |
class des{ |
In the process of using classes, we sometimes need to instantiate multiple fields of the object immediately. If done manually, it will bring many unpredictable problems. If it is executed automatically during the object creation process, it will bring many unpredictable problems. Comes in a lot of convenience.
The PHP constructor function is a function that is automatically executed when a class is instantiated, also called a constructor.
代码如下 | 复制代码 |
function __construct([argument1,argument2,argument3]){ |
The code is as follows | Copy code |
function __construct([argument1,argument2,argument3]){ /* class initialization code */ } |
实例:
代码如下
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class task1{ |
实例: