Protected and const attributes of PHP classes and objects_PHP tutorial

This article will introduce you to the usage of protected and const attributes of classes and objects in PHP. Friends who need to know more can refer to it.

const attribute
A field defined with the const attribute is a constant. Constants in a class are similar to static variables. The difference is that the value of a constant cannot be changed once assigned.

Const definition constant does not need to add the $ symbol, its structure is as follows:

const constant name //Constant names cannot use the $ symbol

Example:

Tip: Constant names defined using const are generally capitalized. This is a convention. We must develop a good naming habit. It is also a convention to use underscore_links if the defined constant consists of more than one word. For example: FILE_SIZE.

The code is as follows

代码如下	复制代码
class Date{   const M="Monday";  }  echo "today is ".Date::M; ?>

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class Date{ const M="Monday"; } echo "today is ".Date::M;

?>

代码如下

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class me{            protected $Money =100;         protected $price1=60;            public function Sell($price){         if($this->price1    echo "好，卖给你了。 ";         $this->Money = $this->Money+$price;      return "我现在总共有 ".$this->Money." 元钱";    }  else{              echo "我不卖 ,$price 太便宜了 ";       return "现在我还是 ".$this->Money." 元钱";      }   }  }    $now=new me;            echo $now->Sell(30);          ?>

protected attribute

The scope of the protected field is between public and private. If the member is declared protected, it means that the field can only be used in this class and subclasses of this class. Example:

The code is as follows

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class me{                                         protected $Money =100; protected $price1=60;  public function Sell($price){  if($this->price1 echo "Okay, I'll sell it to you. "; $this->Money = $this->Money+$price; Return "I now have a total of ".$this->Money." yuan"; } else{                                               echo "I don't want to sell it, $price is too cheap "; return "Now I am still ".$this->Money." yuan"; } } } $now=new me;  echo $now->Sell(30); ?> http://www.bkjia.com/PHPjc/628819.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/628819.htmlTechArticleThis article introduces the usage of protected and const attributes of classes and objects in php. Friends who need to know more can Reference Reference. const attribute A field defined with a const attribute is a constant, class...