Detailed explanation of declaration and instantiation of PHP classes, construction methods and destruction methods_php skills

The examples in this article describe the declaration and instantiation of PHP classes as well as the construction methods and destructor methods. Share it with everyone for your reference, the details are as follows:

<&#63;php
class human{
  public static $leg=2;
  public $name = 'leo';
  public $age = '25';
  public function cry(){
  }
}
$leo = new human();
print_r($leo);
/*返回
human Object ( [name] => leo [age] => 25 )
*/
//为什么没有leg呢？
//是因为加了static，就变成了类的属性了，是属于所有
//通过这个类实例实例后的对象的
//public是权限修饰符，权限修饰符有public,protected,private
//在PHP4经常用到var，这个现在不怎么也不推荐用，就相当于public
//在PHP5中会把var解析成public
&#63;>

Is there any way to change the properties of the object by passing parameters when creating a new object? Rather than being the same

Answer: You can define a constructor method in the class, that is, it will be executed when the object is initialized and can receive parameters

As shown below:

<&#63;php 
class human{
  public static $leg=2;
  public $name = 'leo';
  public $age = '25';
  public function __construct($name,$age){
    $this->name=$name;
    $this->age=$age;
  }
}
$leo = new human('macro','23');
print_r($leo);
/*
返回
human Object ( [name] => macro [age] => 23 )
可以看到参数起作用了
__construct就是构造函数
*/
&#63;>

Corresponding to the constructor is the destructor, which is executed when the object is destroyed

As shown below:

<&#63;php 
class human{
  public static $leg=2;
  public $name = 'leo';
  public $age = '25';
  public function __construct($name,$age){
    $this->name=$name;
    $this->age=$age;
    echo $this->name."对象生成啦<br />";
  }
  public function __destruct(){
    echo $this->name."对象销毁啦<br />";
  }
}
$leo = new human('macro','23');
$tim = new human('tim','18');
unset($leo);
echo '~~~~~~~~~~~~~~~~~~~~<br />';
/*
返回：
macro对象生成啦
tim对象生成啦
macro对象销毁啦
~~~~~~~~~~~~~~~~~~~~
tim对象销毁啦
*/
//__destruct是析构函数，即对象销毁的时候调用
//为什么$tim 没有unset 也执行了析构函数
//这是一个隐式销毁，unset是显式销毁
//当一个页面执行完成自动销毁
&#63;>

Readers who are interested in more about PHP object-oriented content can check out the special topic of this site: "php object-oriented programming introductory tutorial"

I hope this article will be helpful to everyone in PHP programming.