Backend Development
PHP Tutorial
The difference between constants, static properties and non-static properties in PHP
The difference between constants, static properties and non-static properties in PHP
This article mainly introduces the difference and introduction of constants, static properties, and non-static properties in PHP classes. Friends in need can refer to
1. Class constants: always in the class Values that remain unchanged are defined as constants
The constants of the class cannot use access restriction modifiers. They are public, inheritable, and can be overridden by subclasses. Double colons must be used to access the constants of the class: : , can be accessed using the class name or an instance of the class. Because it is a constant, the name cannot use the symbol representing the variable $.
You can define a value that always remains unchanged in the class as a constant. There is no need to use the $ symbol when defining and using constants.
The value of a constant must be a fixed value and cannot be a variable, class attribute, the result of a mathematical operation or a function call.
Constants can also be defined in interfaces. See the interface section of the documentation for more examples.
Since PHP 5.3.0, you can use a variable to dynamically call a class. But the value of this variable cannot be a keyword (such as self, parent or static).
Syntax: const constant= 'constant';
class Myclass{
const constant = '常量';
//类内部调用
public function test(){
echo self::constant.'<br>';
}
}
Myclass::test();
//类外部访问
echo Myclass::constant.'<br>'; //方法一
$obj = new Myclass(); //方法二
echo $obj::constant.'<br>';2. Static attribute: It is a variable and can be constant syntax Access is::, which can be accessed without instantiation
Syntax: public static $my_static = 'similar constant';
class Myclass{
public static $static_val = '静态属性';
//类内部访问
public function test(){
return self::$static_val.'<br>';
}
}
//类外部访问
// echo Myclass::test();
echo Myclass::$static_val; //方法一
$obj = new Myclass(); //方法二
echo $obj::$static_val;
echo $obj->test();3. Non-static properties: A normal variable, which can be accessed after instantiation, using the -> symbol
Syntax: public $my_val = 'normal variable'
class Myclass{
public $normal_val = '非静态属性';
//类内部访问
public function test(){
return $this->normal_val ;
}
}
//类外部访问
$obj = new Myclass();
echo $obj->normal_val;
echo $obj->test();PHP method to obtain the constants, properties, and method lists in a class
$r = new ReflectionClass($this); Zend_Debug::dump($r->getConstants(), "Constants"); Zend_Debug::dump($r->getProperties(), "Properties"); Zend_Debug::dump($r->getMethods(), "Methods");
The above is the entire content of this article, I hope it will be helpful to everyone's study.
Related recommendations:
PHPString definition methods and their differences
php substr function definition and usage summary
2017 php explode function definition and usage summary
The above is the detailed content of The difference between constants, static properties and non-static properties in PHP. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1666
14
1425
52
1325
25
1272
29
1252
24
PHP and Python: Comparing Two Popular Programming Languages
Apr 14, 2025 am 12:13 AM
PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.
PHP: A Key Language for Web Development
Apr 13, 2025 am 12:08 AM
PHP is a scripting language widely used on the server side, especially suitable for web development. 1.PHP can embed HTML, process HTTP requests and responses, and supports a variety of databases. 2.PHP is used to generate dynamic web content, process form data, access databases, etc., with strong community support and open source resources. 3. PHP is an interpreted language, and the execution process includes lexical analysis, grammatical analysis, compilation and execution. 4.PHP can be combined with MySQL for advanced applications such as user registration systems. 5. When debugging PHP, you can use functions such as error_reporting() and var_dump(). 6. Optimize PHP code to use caching mechanisms, optimize database queries and use built-in functions. 7
PHP in Action: Real-World Examples and Applications
Apr 14, 2025 am 12:19 AM
PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.
PHP vs. Python: Understanding the Differences
Apr 11, 2025 am 12:15 AM
PHP and Python each have their own advantages, and the choice should be based on project requirements. 1.PHP is suitable for web development, with simple syntax and high execution efficiency. 2. Python is suitable for data science and machine learning, with concise syntax and rich libraries.
The Enduring Relevance of PHP: Is It Still Alive?
Apr 14, 2025 am 12:12 AM
PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.
PHP and Python: Code Examples and Comparison
Apr 15, 2025 am 12:07 AM
PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.
PHP vs. Other Languages: A Comparison
Apr 13, 2025 am 12:19 AM
PHP is suitable for web development, especially in rapid development and processing dynamic content, but is not good at data science and enterprise-level applications. Compared with Python, PHP has more advantages in web development, but is not as good as Python in the field of data science; compared with Java, PHP performs worse in enterprise-level applications, but is more flexible in web development; compared with JavaScript, PHP is more concise in back-end development, but is not as good as JavaScript in front-end development.
PHP and Python: Different Paradigms Explained
Apr 18, 2025 am 12:26 AM
PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.
