Table of Contents
Briefly talk about unicode and utf8 encoding in php, unicodeutf8
Home Backend Development PHP Tutorial Briefly talk about unicode and utf8 encoding in php, unicodeutf8_PHP tutorial

Briefly talk about unicode and utf8 encoding in php, unicodeutf8_PHP tutorial

Jul 13, 2016 am 09:51 AM
php unicode utf8 coding

Briefly talk about unicode and utf8 encoding in php, unicodeutf8

Re-understand unicode and utf8 encoding

Until today, just now to be precise, I didn’t know that UTF-8 encoding and Unicode encoding are different, there is a difference 囧
There is a certain connection between them, look at their differences:
The length of UTF-8 is not certain, it may be 1, 2, or 3 bytes
Unicode has a certain length, 2 bytes (USC-2)
UTF-8 can be converted to and from Unicode

The relationship between unicode and utf8

Unicode(16)

UTF-8(binary)

0000 - 007F 0xxxxxxx
0080 - 07FF 110xxxxx 10xxxxxx
0800 - FFFF 1110xxxx 10xxxxxx 10xxxxxx

The above table has two meanings. The first one is obviously the correspondence between Unicode and UTF-8 character ranges, and the other one shows how Unicode and UTF-8 are converted to each other:

Let’s talk about UTF-8 to Unicode conversion first

The UTF-8 encoded binary is matched with the above three formats. After matching, the fixed bits (non-x positions in the table) are removed, and then every 8 bits are grouped from right to left. If there are not enough 8 bits, the left side will not be used. , make up 2 bytes and 16 bits. These 16 bits represent the Unicode encoding corresponding to UTF-8. Take a look at the following examples:

The text encoding format in the above picture is UTF-8, and you can use WinHex to see its hexadecimal representation
Copy code The code is as follows:
Character => UTF-8 => UTF-8 binary => Remove the fixed position to make up the 16-bit binary => Hexadecimal

Chinese => E6B189 => 11100110 10110001 10001001 => 01101100 01001001 => 6C49
Word => E5AD97 => 11100101 10101101 10010111 => 01011011 01010111 => 5B57

#The following is the result of running under the chrome command line
'u6C49'
"汉"
'u5B57'
"Word"

#At this point, converting from UTF-8 to Unicode is already a very easy task. Take a look at the pseudocode of the conversion
Read one byte, 11100110
Determine the format of the UTF-8 character, which belongs to the third type, 3 bytes
Continue reading 2 bytes to get 11100101 10101101 10010111
Remove the fixed bits according to the format 1011011 01010111
Not enough 16 digits, add zeros on the left 01011011 01010111 => 5B57

Look again at the conversion from Unicode to UTF-8

Copy code The code is as follows:
5B57
Get the Unicode range where 5B57 is located, 0800 <= 5B57 <= FFFF. It is known that the UTF-8 of 5B57 has three bytes, in the form of 1110xxxx 10xxxxxx 10xxxxxx
Get the binary encoding of 5B57 101101101010111
Use the binary encoding in the previous step to splice UTF-8 encoding from right to left 11100101 10101101 10010111

Talk about the problem

Let’s talk about the cause of today’s problem. Many words are input from the front end. Each word in UTF-8 format has a maximum of 30 bytes, so verification will be done on the front end and backend respectively. JavaScript uses Unicode encoding, and the backend program UTF-8 encoding is used, and the current solution is as follows

Front end

function utf8_bytes(str)
{
 var len = 0, unicode;
 for(var i = 0; i < str.length; i++)
 {
 unicode = str.charCodeAt(i);
 if(unicode < 0x0080) {
  ++len;
 } else if(unicode < 0x0800) {
  len += 2;
 } else if(unicode <= 0xFFFF) {
  len += 3;
 }else {
  throw "characters must be USC-2!!"
 }
 }
 return len;
}

#例子
utf8_bytes('asdasdas')
8
utf8_bytes('yrt燕睿涛')
12

Copy after login

Backstage

#对于GBK字符串
$len = ceil(strlen(bin2hex(iconv('GBK', 'UTF-8', $word)))/2);
#对于UTF8字符串
$len = ceil(strlen(bin2hex($word))/2);
Copy after login

The above is the entire content of this article, I hope you all like it.

www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/1014437.htmlTechArticleBriefly talk about unicode and utf8 encoding in php, unicodeutf8 Re-recognize unicode and utf8 encoding until today, to be precise It was just now that I realized that UTF-8 encoding and Unicode encoding are different...
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)

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

7 PHP Functions I Regret I Didn't Know Before 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

How To Set Up Visual Studio Code (VS Code) for PHP Development 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

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

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

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.

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.

See all articles