What is PHP recursive function and simple example explanation
What is php recursive function?
Recursive function is a self-calling function, which calls itself directly or indirectly within the function body, that is, the nested call of the function is the function itself. Usually, a conditional judgment statement is attached to this type of function to determine whether a recursive call needs to be executed, and the recursive calling action of the function is terminated under specific conditions, and the control of the current process is returned to the previous layer. function to execute. Therefore, when a function that performs a recursive call does not have additional conditional judgment statements, an infinite loop error may occur.
The biggest advantage of recursive function calling is that it can simplify complex repeated calling procedures in the program, and can use this feature to perform some more complex operations. For example, operations such as lists, dynamic tree menus, and directory traversal. The corresponding non-recursive functions, while efficient, are difficult to program and relatively unreadable. The goal of modern programming is primarily readability. With the continuous improvement of computer hardware performance, programs prioritize readability rather than efficiency in more situations. Therefore, the use of recursive functions is encouraged to implement program ideas.
A simple recursive call example is as follows:
<?php
//声明一个函数，用于测试递归
function test($n){
echo $n." "; //在函数开始输出参数的值
if($n>0){ //判断参数是否大于0
test($n-1); //如果参数大于0则调用自己，并将参数减1后再次传入
}else{ //判断参数是不大于0
echo "<--------> ";
}
echo $n." ";
}
test(10); //调用test函数将整数10传给参数
?>After the program is executed, the following results are output:
10 9 8 7 6 5 4 3 2 1 0 <--------> 0 1 2 3 4 5 6 7 8 9 10
Find the reason why the numbers in the second half of the result are output in forward order
Explanation: In the above example, a test() function is declared, which requires an integer parameter. Call the test() function outside the function by passing the integer 10 as argument. In the test() function body, the first code outputs the value of the parameter and a space. Then determine whether the condition is true, and if so, call yourself and reduce the parameter by 1 and pass it in again. When it starts to be called, it calls the outer layer to the inner layer, and the inner layer calls to the inner layer until the innermost layer must end due to conditions not allowing it. When the most memory is finished, <--------> is output as a delimiter. The code after executing the call outputs the value of the parameter and a space, and it will return to the outer layer to continue execution. When the outer layer ends, return to the outer layer and continue execution, pushing out layer by layer until the outermost layer ends. The result after the execution is completed is the result we saw above.
The above is the explanation of PHP recursive functions and simple examples. In the next chapter, we will introduce Three methods of implementing recursive functions in PHP.
【Recommended related tutorials】
1. "php.cn Dugu Jiujian (4)-php video tutorial"
2. php programming from entry to mastering a full set of video tutorials
3. php practical video tutorial
The above is the detailed content of What is PHP recursive function and simple example explanation. 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
PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian
Dec 24, 2024 pm 04:42 PM
PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati
How To Set Up Visual Studio Code (VS Code) for PHP Development
Dec 20, 2024 am 11:31 AM
Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c
Explain JSON Web Tokens (JWT) and their use case in PHP APIs.
Apr 05, 2025 am 12:04 AM
JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,
PHP Program to Count Vowels in a String
Feb 07, 2025 pm 12:12 PM
A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total
Explain late static binding in PHP (static::).
Apr 03, 2025 am 12:04 AM
Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.
How do you parse and process HTML/XML in PHP?
Feb 07, 2025 am 11:57 AM
This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an
What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases?
Apr 03, 2025 am 12:03 AM
What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.
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.
