How is the PHP array implemented at the C level?
PHP Array Implementation on the C Level
The PHP array is a fundamental data structure in PHP, boasting versatility and efficient performance. However, some array functions exhibit slower speeds than expected, leading to the question: How is the PHP array implemented at the C level?
Delving into the PHP core, specifically zend/zend_hash.h and ext/standard/array.c, reveals that the PHP array employs a chained hash table. This structure provides constant-time lookup (O(c)) and handles key collisions through linear search (O(n)). The hashing algorithm accommodates both integer and string keys within the same key space.
Each stored value in the hash links to its preceding and succeeding values, creating a linked list. Additionally, a temporary pointer tracks the current item for seamless iteration.
Regarding array_rand, its inherent randomness dictates iterating over the array randomly (O(n)) to ensure a truly random key. This is due to potential missing keys in the range, making direct key access (O(c)) impossible.
Furthermore, array_key_exists and in_array differ in implementation. array_key_exists utilizes hash lookup, resulting in O(c) performance, while in_array resorts to linear search (O(n)), which becomes inefficient for large arrays.
In summary, the PHP array offers efficient hash-based lookup. However, its linked list structure impacts scalar array operations such as array_rand, particularly noticeable with large arrays. The absence of a clear flag for array creation using array subscript or array_push that would enable C array-like scaling presents an opportunity for potential performance improvements in specific scenarios.
The above is the detailed content of How is the PHP array implemented at the C level?. 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
Alipay PHP SDK transfer error: How to solve the problem of 'Cannot declare class SignData'?
Apr 01, 2025 am 07:21 AM
Alipay PHP...
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,
Describe the SOLID principles and how they apply to PHP development.
Apr 03, 2025 am 12:04 AM
The application of SOLID principle in PHP development includes: 1. Single responsibility principle (SRP): Each class is responsible for only one function. 2. Open and close principle (OCP): Changes are achieved through extension rather than modification. 3. Lisch's Substitution Principle (LSP): Subclasses can replace base classes without affecting program accuracy. 4. Interface isolation principle (ISP): Use fine-grained interfaces to avoid dependencies and unused methods. 5. Dependency inversion principle (DIP): High and low-level modules rely on abstraction and are implemented through dependency injection.
How to automatically set permissions of unixsocket after system restart?
Mar 31, 2025 pm 11:54 PM
How to automatically set the permissions of unixsocket after the system restarts. Every time the system restarts, we need to execute the following command to modify the permissions of unixsocket: sudo...
How to debug CLI mode in PHPStorm?
Apr 01, 2025 pm 02:57 PM
How to debug CLI mode in PHPStorm? When developing with PHPStorm, sometimes we need to debug PHP in command line interface (CLI) mode...
How to send a POST request containing JSON data using PHP's cURL library?
Apr 01, 2025 pm 03:12 PM
Sending JSON data using PHP's cURL library In PHP development, it is often necessary to interact with external APIs. One of the common ways is to use cURL library to send POST�...
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.
Explain the concept of late static binding in PHP.
Mar 21, 2025 pm 01:33 PM
Article discusses late static binding (LSB) in PHP, introduced in PHP 5.3, allowing runtime resolution of static method calls for more flexible inheritance.Main issue: LSB vs. traditional polymorphism; LSB's practical applications and potential perfo
