PHP Static Properties

Understanding Static Properties in PHP OOP （了解PHP OOP中的静态属性）

Object Oriented Programming (OOP) is a programming paradigm that allows developers to create objects, which can be treated as instances of a class. The class can be seen as a blueprint for creating these objects. One of the important concepts in OOP is the use of properties, which are used to store data and information about the objects. In this article, we will dive into static properties in PHP OOP and how they are used. （面向对象编程（ OOP ）是一种编程范式，允许开发人员创建对象，可以将其视为类的实例。类可以被视为创建这些对象的蓝图。OOP中的一个重要概念是使用属性，用于存储有关对象的数据和信息。在本文中，我们将深入探讨PHP OOP中的静态属性及其使用方式。）

What are Static Properties in PHP OOP? #

What are Static Properties in PHP OOP? （PHP OOP中的静态属性是什么？）

Static properties are properties that belong to the class itself, rather than to an instance of the class. In other words, they are shared between all instances of a class. They are accessed using the class name, rather than an instance of the class. （静态属性是属于类本身而不是类实例的属性。换句话说，它们在类的所有实例之间共享。访问它们时使用类名，而不是类的实例。）

<?php

class User {
   public static $count = 0;
   public function __construct() {
       self::$count++;
   }
}

$user1 = new User();
$user2 = new User();

echo User::$count; // Outputs: 2

?>

In the example above, we have created a User class with a static property $count. Every time a new instance of the User class is created, the $count property is incremented. Since the $count property is static, it is shared between all instances of the User class and can be accessed using the class name, User. （在上面的示例中，我们创建了一个具有静态属性$ count的User类。每次创建User类的新实例时， $ count属性都会递增。由于$ count属性是静态的，因此它在User类的所有实例之间共享，可以使用类名User进行访问。）

Why Use Static Properties in PHP OOP? #

Why Use Static Properties in PHP OOP? （为什么要在PHP OOP中使用静态属性？）

Static properties are useful in certain situations where you need to store information that is shared between all instances of a class. For example, you may want to keep track of the total number of instances that have been created for a particular class. （在需要存储类所有实例之间共享的信息的某些情况下，静态属性非常有用。例如，您可能希望跟踪为特定类创建的实例总数。）

Static properties are also useful for creating constant values, which cannot be changed after they are defined. （静态属性对于创建常量值也很有用，常量值在定义后无法更改。）

<?php

class User {
   const MAX_USERS = 100;
}

echo User::MAX_USERS; // Outputs: 100

?>

In the example above, we have created a constant MAX_USERS in the User class. The constant value cannot be changed after it is defined. （在上面的示例中，我们在User类中创建了一个常量MAX_USERS。常量值在定义后无法更改。）

Conclusion #

Conclusion （小结）

Static properties in PHP OOP are a powerful tool for developers. They allow you to store information that is shared between all instances of a class, and are useful for keeping track of the total number of instances or for creating constant values. By understanding the use of static properties, you can create more efficient and organized code in your PHP OOP projects. （PHP OOP中的静态属性对于开发人员来说是一个强大的工具。它们允许您存储在类的所有实例之间共享的信息，并且对于跟踪实例总数或创建常量值非常有用。通过了解静态属性的使用，您可以在PHP OOP项目中创建更有效和更有组织的代码。）