Pseudotypes and pseudovariables in PHP
1. Pseudo-types
There are three PHP pseudo-types, namely: 1, mixed type. 2. number digital type. 3. callbackCallback type.
1, mixed mixed type:
mixed indicates that a parameter can accept multiple different types, but not all types.
2, number numeric type:
The number parameter can accept integer integer type and floatFloating point type.
3, callback type:
For example, the call_user_func() function can receive a user-defined function as a parameter, which is php A built-in function. The callback function can not only be a function, but also a method of an object and a method of a static class. A php function is passed using the function namestring. Any built-in or user-defined function can be passed, except language structures such as array(), echo(), empty() ,eval(),exit(),isset(),list(),print(),unset(), etc.
If you want to pass in the method of an object, it needs to be passed in the form of an array. The array subscript 0 is the object name and the subscript 1 is the method name. If there is no static class instantiated as an object, to pass its method, replace the object name specified by the array 0 subscript with the name of the class.
In addition to ordinary user-defined functions, you can also use create_function to create an anonymous callback function.
Example::
<?php
//普通的回调函数
function my_callback_function(){
echo "my is callback function.";
}
//回调方法
class MyClass{
static function myCallbackMethod(){
echo "my is callback method.";
}
}
//num1:回调函数
call_user_func('my_callback_function');
//num2:静态类的方法
call_user_func(array('MyClass','myCallbackMethod'));
//num3:对象方法
$obj = new MyClass();
call_user_func(array($obj,'myCallbackMethod'));
//num4:静态类的方法（5.3.0以上）
call_user_func('MyClass::myCallbackMethod');
//num5:相对静态方法调用
class A {
public static function who(){
echo "A";
}
}
class B extends A {
public static function who(){
echo "B";
}
}
call_user_func(array('B','parent::who')); //输出B
//num6:调用时传入参数
function test($a,$b){
echo $a;
echo $b;
}
call_user_function('test','1','2'); //输出1 2
//num7:调用类方法传入参数
class a(){
function b($c){
echo $c;
}
}
call_user_func(array('a','b'),'1'); //输出1
//num8:call_user_func_array与call_user_func很相似，只不过换了一种方式传递参数，让参数结构更清晰：
function a($b,$c){
echo $b;
echo $c;
}
call_user_func_array('a',array('1','2')); //输出1 2
//num9:用call_user_func_array调用类内部方法
class A(){
function a($b,$c){
echo $b;
echo $c;
}
}
call_user_func_array(array('A','a'),array('1','2')); //输出1 2
//num10:call_user_func函数和call_user_func_array函数都支持引用，这让他们和普通的函数调用更趋于功能一致：
function a($b){
$b++;
}
$c=0;
call_user_func('a',$c); //输出1
call_user_func('a',array($c)); //输出2
2. Pseudo variables
$... in php is pseudo Variable means etc. This variable name is used when a function can accept any number of parameters.
The above is the detailed content of Pseudotypes and pseudovariables 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
1668
14
1428
52
1329
25
1273
29
1256
24
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 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.
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 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.
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: 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.
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: 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.
