PHP class attributes and class constants-headlines-php.cn

*Class attributes and class constants

* 1. Class attributes only allow the following types of data to be initialized

* Scalar and array literals: strings, values, constants, arrays , Prototype document (php5.3)

* 2. Not allowed to use: variables, expressions, objects

* 3. Class constants are declared using the keyword const, and access restrictions are not allowed to be set , forced to be public and cannot be changed

* 4. Class constants are attribute classes and do not attribute to one of its instance objects. They must be accessed using classes

* 5. Access class constants To use the range parsing character::, double colon

* Use the keyword self in the class to indicate the current class, and the class name can be used directly externally

define('SITE_NAME','PHP中文网'); class User1 { //声明属性 private $siteName = SITE_NAME; private $name = '老顽童'; private $email = 'lwt@php.cn'; private $course = ['php','java','python']; const LECTURE = '朱老师'; //构造方法 public function __construct($name='',$email='', $siteName='',array $course=[]) { //如果传参,则使用新值初始化属性,否则使用默认值 $name ? ($this->name = $name) : $this->name; $email ? ($this->email = $email) : $this->email; $siteName ? ($this->siteName = $siteName) : $this->siteName; $course ? ($this->course = $course) : $this->course; } //查询器 public function __get($name) { return $this->$name; } //设置器 public function __set($name,$value) { return $this->$name = $value; } //在类中访问类常量,使用self来引用当前类名 public function getConst() { //类内部也可以直接使用当前类名 // return User1::LECTURE; //推荐使用self:当类名改变时,不必修改内部对它的引用 return self::LECTURE; } }

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