Home Backend Development PHP Tutorial Detailed explanation of examples of random shuffling and reverse ordering of PHP arrays

Detailed explanation of examples of random shuffling and reverse ordering of PHP arrays

May 04, 2017 am 11:38 AM

Random shuffling and reverse order of PHP arrays

In the first two articles "How to sort PHP arrays" and " PHP Array Reverse Order" introduces two sets of functions, one in ascending order and one in reverse order (descending order). Today, in this article, we will introduce to you the random order and reverse order of arrays!

1. What is random disorder? (shuffle)

#shuffle is to disrupt the array.

Use the shuffle function to randomly sort the elements in the array.

The shuffle syntax structure is as follows:

1

bool shuffle ( array &$array )

Copy after login
ParametersDescription
arrayRequired. Specifies the array to adapt to.

This function scrambles (randomly arranges the order of cells) an array. It uses a pseudo-random number generator and is not suitable for cryptography situations.

shuffle instance usage:

Let’s take an example to explain the shuffle function in detail. The specific code is as follows:

1

2

3

4

5

6

<?php

header("Content-Type:text/html; charset=utf-8");

$arr=array("name" => "PHP中文网", "url" => "www.php.cn", "tom" => "100","hank" => "60");

shuffle($arr); // 将数组的值随机排序

print_r($arr);

?>

Copy after login

The output result is:

Detailed explanation of examples of random shuffling and reverse ordering of PHP arrays

The above example will output different results every time you refresh the browser. I won’t take more screenshots here. You can try it locally!

Note: After the associative array is shuffled, the keys will be lost, as you should be able to see from the above example!

2. What is reverse order? (array_reverse)

array_reverse — Returns an array with the reverse order of the cells. Reverse order is to reverse the order of each element in an original array,

The syntax format of array_reverse is as follows:

1

array array_reverse ( array $array [, bool $preserve_keys = false ] )

Copy after login

array_reverse() accepts array array as input and returns a new array with the cells in reverse order. If preserve_keys is TRUE, the original key names are retained.

Instructions:

1. Reverse order ≠ Descending order

2. If The array is an associative array

When the key is a character, the reverse order will not be affected, the key will still be retained

When the key is a number, after the reverse order The default keys will be reset to 0, 1, 2...

When the second parameter is true, the keys are numbers, and the numeric keys are retained in reverse order

Let’s look at the example code of when the key is a number:

1

2

3

4

5

6

7

8

<?php

header("Content-Type:text/html; charset=utf-8");

$arr=array("100" => "PHP中文网", "200" => "www.php.cn", "300" => "百度","400" => "搜狗");

$array = array_reverse($arr);//数组反序,将数组的元素反转

print_r($arr);

echo "<br>";

print_r($array);

?>

Copy after login

The output result is:

Detailed explanation of examples of random shuffling and reverse ordering of PHP arrays

The key is Keep the key value when numbersSample code:

1

2

3

4

5

6

7

8

<?php

header("Content-Type:text/html; charset=utf-8");

$arr=array("100" => "PHP中文网", "200" => "www.php.cn", "300" => "百度","400" => "搜狗");

$array = array_reverse($arr,true);//数组反序,将数组的元素反转

print_r($arr);

echo "<br>";

print_r($array);

?>

Copy after login

The output result is:

Detailed explanation of examples of random shuffling and reverse ordering of PHP arrays

As can be seen from the above code, the key is When numbers are used, the key value is retained, which means the second parameter of array_reverse is true!

The key is when the key is a characterSample code:

1

2

3

4

5

6

7

8

<?php

header("Content-Type:text/html; charset=utf-8");

$arr=array("name" => "PHP中文网", "ID" => "www.php.cn", "name1" => "百度","name2" => "搜狗");

$array = array_reverse($arr);//数组反序,将数组的元素反转

print_r($arr);

echo "<br>";

print_r($array);

?>

Copy after login

The output result is:

Detailed explanation of examples of random shuffling and reverse ordering of PHP arrays

array_reverse function When the array is reversed, if the key value is a string, the key value will be retained!

Note: When using the array_reverse function, the original array will not be affected, and a new array will be returned!

In this article we introduce the reverse order and disorder of the array. In the next article, we will introduce the equal division, replacement and interception of arrays. For detailed introduction, please read "Interception, equal division and replacement of partial arrays of PHP arrays"!

【Related tutorial recommendations】

  1. Related topic recommendations: "php array (Array)"

  2. Related video course recommendations: "Other array functions: array_rand()/array_sum()/shuffle()/range()


The above is the detailed content of Detailed explanation of examples of random shuffling and reverse ordering of PHP arrays. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial
1655
14
PHP Tutorial
1254
29
C# Tutorial
1228
24
PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian 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

Explain JSON Web Tokens (JWT) and their use case in PHP APIs. 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,

How do you parse and process HTML/XML in PHP? 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

Explain late static binding in PHP (static::). 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.

PHP Program to Count Vowels in a String 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

PHP and Python: Comparing Two Popular Programming Languages 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.

What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? 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: A Key Language for Web Development 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

See all articles