Home Backend Development PHP Problem Common methods of php arrays

Common methods of php arrays

May 23, 2023 pm 12:20 PM

In PHP development, array is a very commonly used data type. A PHP array is an ordered collection used to store a set of values. During the application development process, it is often necessary to operate on arrays, including operations such as adding, deleting, modifying, and querying. This article will introduce common methods of PHP arrays.

  1. Creating Arrays

There are two ways to create PHP arrays: ordinary arrays and associative arrays.

Ordinary arrays access element values ​​by specifying the index number of the element, while associative arrays access element values ​​by specifying string key names.

Create a normal array:

// 方式1
$arr1 = array("a", "b", "c");
// 方式2
$arr2 = ["a", "b", "c"];
Copy after login

Create an associative array:

// 方式1
$arr1 = array("name" => "John", "age" => 30, "country" => "USA");
// 方式2
$arr2 = ["name" => "John", "age" => 30, "country" => "USA"];
Copy after login
  1. Access array elements

You can use square brackets to access array elements [] operator. For a normal array, you can access elements using numeric indexes, and for associative arrays, you can access elements using key names.

// 访问普通数组
$arr = ["a", "b", "c"];
echo $arr[0]; // 输出a
echo $arr[1]; // 输出b
echo $arr[2]; // 输出c
 
// 访问关联数组
$user = ["name" => "John", "age" => 30, "country" => "USA"];
echo $user["name"]; // 输出John
echo $user["age"]; // 输出30
echo $user["country"]; // 输出USA
Copy after login
  1. Array length

PHP provides the count() function to get the length of the array.

$arr = ["a", "b", "c"];
echo count($arr); // 输出3
Copy after login
  1. Add elements

Elements can be added to the array through the square brackets [] operator.

// 添加元素到普通数组
$arr = ["a", "b", "c"];
$arr[] = "d"; // 在数组末尾添加元素d
print_r($arr); // 输出Array ( [0] => a [1] => b [2] => c [3] => d )
 
// 添加元素到关联数组
$user = ["name" => "John", "age" => 30];
$user["country"] = "USA"; // 添加元素到关联数组
print_r($user); // 输出Array ( [name] => John [age] => 30 [country] => USA )
Copy after login
  1. Delete elements

You can delete elements in the array through the unset() function. For ordinary arrays, after deleting an element, the index numbers in the array will be reordered; for associative arrays, after deleting an element, the key names of all subsequent elements will be automatically adjusted.

// 删除普通数组中的元素
$arr = ["a", "b", "c"];
unset($arr[1]); // 删除索引号为1的元素b
print_r($arr); // 输出Array ( [0] => a [2] => c )
 
// 删除关联数组中的元素
$user = ["name" => "John", "age" => 30, "country" => "USA"];
unset($user["age"]); // 删除键名为age的元素
print_r($user); // 输出Array ( [name] => John [country] => USA )
Copy after login
  1. Modify elements

You can modify elements in the array through the square brackets [] operator.

// 修改普通数组中的元素
$arr = ["a", "b", "c"];
$arr[1] = "d"; // 把索引号为1的元素b改为d
print_r($arr); // 输出Array ( [0] => a [1] => d [2] => c )
 
// 修改关联数组中的元素
$user = ["name" => "John", "age" => 30, "country" => "USA"];
$user["age"] = 31; // 把键名为age的元素30改为31
print_r($user); // 输出Array ( [name] => John [age] => 31 [country] => USA )
Copy after login
  1. Traversing arrays

PHP provides a variety of ways to traverse arrays, including for loops, foreach loops, and while loops. Among them, the foreach loop is most commonly used when processing arrays.

// for循环遍历普通数组
$arr = ["a", "b", "c"];
for ($i = 0; $i < count($arr); $i++) {
    echo $arr[$i] . "
";
} // 输出a b c
 
// foreach循环遍历普通数组
$arr = ["a", "b", "c"];
foreach ($arr as $value) {
    echo $value . "
";
} // 输出a b c
 
// foreach循环遍历关联数组
$user = ["name" => "John", "age" => 30, "country" => "USA"];
foreach ($user as $key => $value) {
    echo $key . ": " . $value . "
";
} // 输出name: John age: 30 country: USA
Copy after login

The above are the common methods of PHP arrays. Mastering these methods can better handle array type data often used in PHP applications.

The above is the detailed content of Common methods 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)

OWASP Top 10 PHP: Describe and mitigate common vulnerabilities. OWASP Top 10 PHP: Describe and mitigate common vulnerabilities. Mar 26, 2025 pm 04:13 PM

The article discusses OWASP Top 10 vulnerabilities in PHP and mitigation strategies. Key issues include injection, broken authentication, and XSS, with recommended tools for monitoring and securing PHP applications.

PHP 8 JIT (Just-In-Time) Compilation: How it improves performance. PHP 8 JIT (Just-In-Time) Compilation: How it improves performance. Mar 25, 2025 am 10:37 AM

PHP 8's JIT compilation enhances performance by compiling frequently executed code into machine code, benefiting applications with heavy computations and reducing execution times.

PHP Secure File Uploads: Preventing file-related vulnerabilities. PHP Secure File Uploads: Preventing file-related vulnerabilities. Mar 26, 2025 pm 04:18 PM

The article discusses securing PHP file uploads to prevent vulnerabilities like code injection. It focuses on file type validation, secure storage, and error handling to enhance application security.

PHP Encryption: Symmetric vs. asymmetric encryption. PHP Encryption: Symmetric vs. asymmetric encryption. Mar 25, 2025 pm 03:12 PM

The article discusses symmetric and asymmetric encryption in PHP, comparing their suitability, performance, and security differences. Symmetric encryption is faster and suited for bulk data, while asymmetric is used for secure key exchange.

PHP Authentication & Authorization: Secure implementation. PHP Authentication & Authorization: Secure implementation. Mar 25, 2025 pm 03:06 PM

The article discusses implementing robust authentication and authorization in PHP to prevent unauthorized access, detailing best practices and recommending security-enhancing tools.

PHP API Rate Limiting: Implementation strategies. PHP API Rate Limiting: Implementation strategies. Mar 26, 2025 pm 04:16 PM

The article discusses strategies for implementing API rate limiting in PHP, including algorithms like Token Bucket and Leaky Bucket, and using libraries like symfony/rate-limiter. It also covers monitoring, dynamically adjusting rate limits, and hand

PHP Input Validation: Best practices. PHP Input Validation: Best practices. Mar 26, 2025 pm 04:17 PM

Article discusses best practices for PHP input validation to enhance security, focusing on techniques like using built-in functions, whitelist approach, and server-side validation.

PHP CSRF Protection: How to prevent CSRF attacks. PHP CSRF Protection: How to prevent CSRF attacks. Mar 25, 2025 pm 03:05 PM

The article discusses strategies to prevent CSRF attacks in PHP, including using CSRF tokens, Same-Site cookies, and proper session management.

See all articles