PHP common function analysis: in_array()
In PHP, the in_array() function is a very commonly used function, which can determine whether a value exists in an array. In this article, we will provide an in-depth analysis of the in_array() function.
The syntax of the in_array() function is as follows:
bool in_array(mixed $needle, array $haystack[, bool $strict = FALSE])
where $needle is The value to retrieve, $haystack is the target array, $strict indicates whether to use strict mode (that is, whether to consider types), the default is FALSE.
Next, let’s take a look at an example:
$fruits = array("apple", "banana", "orange");
if (in_array("apple", $fruits)) {
echo "有苹果哦！";
}The output of this code will be “There are apples!” because “apple” exists in the $fruits array.
Next, let’s look at some different situations.
Case 1: For simple value types, the in_array() function uses relaxed mode by default, that is, the type will not be considered. For example:
$numbers = array(1, 2, 3, 4, 5);
if (in_array("2", $numbers)) { // 注意，这里的 2 是一个字符串
echo "2 存在于数组中";
}The output result of this code will also be "2 exists in the array", even if "2" is a string, it can be matched successfully.
To use strict mode, you need to set the third parameter to TRUE. For example:
$numbers = array(1, 2, 3, 4, 5);
if (in_array("2", $numbers, TRUE)) {
echo "2 存在于数组中";
} else {
echo "2 不是数组的元素";
}The output of this code will be "2 is not an element of the array" because in strict mode, "2" and 2 are different types and cannot be matched successfully.
Case 2: For values of composite types (for example, arrays), the in_array() function also uses relaxed mode by default, that is, as long as one of the elements matches successfully, the entire value will be considered a successful match. . For example:
$person1 = array("name" => "John", "age" => 30);
$person2 = array("name" => "Mary", "age" => 25);
$people = array($person1, $person2);
if (in_array(array("name" => "John"), $people)) {
echo "有一个人叫 John！";
}The output of this code will be "There is a person named John!" because the "name" element of $person1 is matched successfully.
Case 3: When the value in the target array is NULL, the in_array() function does not consider that the value does not exist. For example:
$values = array("a", "b", NULL);
if (in_array(NULL, $values)) {
echo "NULL 存在于数组中";
}The output of this code will be "NULL exists in array".
In summary, the in_array() function is a very practical function and is widely used. When you need to determine whether a value exists in an array during development, you can give priority to using this function. At the same time, be careful to use strict mode to avoid type mismatch problems.
The above is the detailed content of PHP common function analysis: in_array(). 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
1386
52
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
7 PHP Functions I Regret I Didn't Know Before
Nov 13, 2024 am 09:42 AM
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
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?
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
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.
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.
