PHP recursive algorithm simplified
Recursive function is a self-calling function. It calls itself directly or directly in the function body, but the conditions for self-calling need to be set. If the conditions are met, the function itself will be called. If not, it will stop. The self-call of this function then returns the control of the current process to the upper-layer function for execution. Maybe it is still difficult to understand if it is explained to us in this way.
For example, the code:
function test ($n){ echo $n." "; if($n>0){ test($n-1); }else{ echo ""; } echo $n." " } test(2)
The final output result of this example is 2 1 0<–>0 1 2
Let me explain why The output is like this
The first step is to execute test(2), echo 2, and then because 2>0, execute test(1), and there is still echo 2 that has not had time to execute
The second step , execute test (1), echo 1, and then because 1>0, execute test (0), and there is also echo 1 that has not had time to execute
The third step, execute test (0), echo 0, execute test (0), echo 0, now the condition of 0>0 is not satisfied, the test() function is no longer executed, but echo "", and the subsequent echo 0
is now no longer called by the function. , start to return the control of the process to the upper layer function for execution, that is, start to execute the last echo that all the test() functions just did not have time to output, the layer of 0 is 1, that is, the layer that outputs 1 1 The previous layer is 2, which means the output is 2 2. There is no previous layer, so the output content is 2 1 0<–>0 1 2
##Related reading:
php recursive algorithm: php recursive algorithm PHP tree - no recursion required: /*** Create parent node treeArray* Parameter* $ar array...
php recursive algorithm Commonly used algorithms for PHP interviews
php recursive algorithm:php recursive algorithm PHP interview Commonly used algorithms...php recursive algorithm based on PHP WeChat red envelope algorithm discussion
php recursive algorithm:php recursive algorithm based on PHP WeChat red envelope algorithm discussion : On a whim, I sent a red envelope to the alumni WeChat group. I set the total amount of the red envelope to 10 yuan, and supported 28 people to receive it randomly. ......The above is the detailed content of PHP recursive algorithm simplified. 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 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

If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op

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

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,

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

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

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.

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.
