Backend Development
PHP Tutorial
Briefly introduce the difference between strlen and mb_strlen in php
Briefly introduce the difference between strlen and mb_strlen in php
Commonly used functions in php to calculate string length are: strlen and mb_strlen. When the characters are all English characters, the two are Same. Here we mainly compare the two calculation results when Chinese and English are mixed.
In PHP, strlen and mb_strlen are functions to find the length of a string, but for some beginners, if they don’t read the manual, they may not be clear about the difference.
The following is an example to explain the difference between the two.
Look at the example first:
<?php //测试时文件的编码方式要是UTF8 $str='中文a字1符'; echo strlen($str).'<br>';//14 echo mb_strlen($str,'utf8').'<br>';//6 echo mb_strlen($str,'gbk').'<br>';//8 echo mb_strlen($str,'gb2312').'<br>';//10 ?>
Result analysis: When calculating strlen, a UTF8 Chinese character is treated as 3 lengths, so the length of "Chinese a character 1 character" is 3*4+ 2=14. When calculating mb_strlen, if the internal code is selected as UTF8, a Chinese character will be calculated as a length of 1, so the length of "Chinese a character 1 character" is 6.
Use these two A function can jointly calculate the occupancy of a mixed Chinese and English string (the occupancy of a Chinese character is 2, and the occupancy of an English character is 1)
echo (strlen($str) + mb_strlen($str,'UTF8')) / 2;
For example, "Chinese a character 1 character" The value of strlen($str) is 14, and the value of mb_strlen($str) is 6. Then it can be calculated that the placeholder for "Chinese a character 1 character" is 10.
echo mb_internal_encoding();
PHP's built-in string length function strlen Doesn't handle Chinese strings correctly, all it gets is the number of bytes occupied by the string. For GB2312 Chinese encoding, the value obtained by strlen is twice the number of Chinese characters, while for UTF-8 encoded Chinese, the difference is three times (under UTF-8 encoding, one Chinese character occupies 3 bytes).
Using the mb_strlen function can better solve this problem. The usage of mb_strlen is similar to strlen, except that it has a second optional parameter to specify the character encoding. For example, to get the UTF-8 string $str length, you can use mb_strlen($str,'UTF-8'). If the second parameter is omitted, PHP's internal encoding will be used. The internal encoding can be obtained through the mb_internal_encoding() function.
It should be noted that mb_strlen is not a core function of PHP. Before using it, you need to make sure that php_mbstring.dll is loaded in php.ini, that is, make sure that "extension=php_mbstring.dll" A line exists and is not commented, otherwise an undefined function problem will occur.
The above is the detailed content of Briefly introduce the difference between strlen and mb_strlen in php. 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
1664
14
1422
52
1316
25
1267
29
1240
24
PHP and Python: Different Paradigms Explained
Apr 18, 2025 am 12:26 AM
PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.
PHP: Handling Databases and Server-Side Logic
Apr 15, 2025 am 12:15 AM
PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.
PHP's Purpose: Building Dynamic Websites
Apr 15, 2025 am 12:18 AM
PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.
Choosing Between PHP and Python: A Guide
Apr 18, 2025 am 12:24 AM
PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.
PHP and Python: A Deep Dive into Their History
Apr 18, 2025 am 12:25 AM
PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.
Why Use PHP? Advantages and Benefits Explained
Apr 16, 2025 am 12:16 AM
The core benefits of PHP include ease of learning, strong web development support, rich libraries and frameworks, high performance and scalability, cross-platform compatibility, and cost-effectiveness. 1) Easy to learn and use, suitable for beginners; 2) Good integration with web servers and supports multiple databases; 3) Have powerful frameworks such as Laravel; 4) High performance can be achieved through optimization; 5) Support multiple operating systems; 6) Open source to reduce development costs.
PHP's Impact: Web Development and Beyond
Apr 18, 2025 am 12:10 AM
PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip
PHP vs. Python: Use Cases and Applications
Apr 17, 2025 am 12:23 AM
PHP is suitable for web development and content management systems, and Python is suitable for data science, machine learning and automation scripts. 1.PHP performs well in building fast and scalable websites and applications and is commonly used in CMS such as WordPress. 2. Python has performed outstandingly in the fields of data science and machine learning, with rich libraries such as NumPy and TensorFlow.
