Blood cases caused by < meta charset=UTF-8> -- Analysis of common character codes

<meta charset="UTF-8"> What does that mean? ？

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I'm looking for an internship recently , Time is limited , In the future, we must write down the underlying principles clearly

First, explain the meaning of this code ：

<meta charset="UTF-8">

• meta Label head Sub tags in

• Set Web page file Display time Character set used

   

List of common character codes

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Code name	explain	remarks
ASCII		1、ASCII Encode each letter or symbol in 1byte（8bits）, also 8bits The highest place is zero 0, therefore ASCII The only letters and symbols that can be coded are 128 individual . There are some coding handles 8bits The highest bit is 1 After 128 Values are also encoded , bring 1byte Can be said 256 It's worth , But this is extended ASCII, Not standard ASCII. Generally speaking, the standard ASCII Only the front 128 It's worth . 2、ASCII The code is compatible with almost all the codes in the world （UTF16 and UTF32 The exception is ）, So if the contents of a text document are all composed of ASCII The letters or symbols inside make up , No matter how you show the content of the document , There can be no garbled code . 3、 Half angle -> A byte （ english ）->ASCII-> The compiler knows
Unicode	unicode	1、 International standard character set , It defines a unique code for each character in various languages in the world , To meet cross language needs 、 Cross platform text information conversion . 2、UTF8 The way to solve the separation between characters is that the highest bit in the number binary is continuous 1 To determine how many bytes this word is encoded .0 The beginning is a single byte , and ASCII Code coincidence , Compatible .
UTF-8（16/32）	UTF-8 It is one of the most widely used  Unicode Of Realization way	take Unicode The abstract code bits of the character set are mapped to 8(16/32) Bit long integers ( Code bit ) A sequence of data storage or transmission .
GB2312		1、GB Full name GuoBiao National standard ,GBK Full name GuoBiaoKuozhan National standard extension .GB18030 Encoding compatibility GBK,GBK compatible GB2312, These three codes have a very deep origin . 2、 The earliest national standard for simplified Chinese character coding , Double byte encoding is adopted , Included 7445 Graphic characters , These include 6763 The Chinese characters . 3、GB2312: Full angle -> Two bytes -> The compiler doesn't know
BIG5		Taiwan Traditional Chinese standard character set , Double byte encoding is adopted , Collects 13053 Chinese characters
GBK		It's right GB2312 Expansion of coding , On Chinese characters Double byte encoding is adopted .GBK The character set contains 21003 The Chinese characters , Including national standards GB13000-1 All the Chinese, Japanese and Korean characters in , and BIG5 All Chinese characters in the code .
GB18030 code		It's right GBK Expansion of coding , Cover Chinese 、 Japanese 、 Korean and Chinese minority languages , It includes 27484 The Chinese characters .GB18030 Character set Use single byte 、 Characters are encoded in three ways: double byte and four byte . compatible GBK and GB2312 Character set

surface 1 Common character coding table

Compatibility column

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chart 1 A list of common character encoding compatibility

  In the picture we can see that ,ASCII Compatible with all codes , and The most common UTF8 And GBK In addition to ASCII There is no intersection outside the part , This is also the most common scenario leading to garbled code in normal business , Use UTF8 Read out GBK Encoded text , You may see all kinds of garbled code . and GB Several codes of series ,GB18030 compatible GBK,GBK Compatible GB2312.

quote ：

1、https://zhuanlan.zhihu.com/p/46216008

2、https://www.qqxiuzi.cn/bianma/zifuji.php