blocks|key|399824|text|您需要这行代码，因为您需要告诉编译器源代码使用哪种编码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|399825|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You need the line since you need to tell the compiler which encoding the source code uses.

blocks|key|2222545|text|您所链接的PEP的摘要确实说明了这一切：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2222546|这个PEP建议引入一个语法来声明源文件的编码。然后，解析器使用编码信息来使用给定的编码来解释文件。最值得注意的是，这增强了对源代码中Unicode文字的解释，并使使用例如UTF-8直接在Unicode感知编辑器中编写Unicode文字成为可能。|blockquote|offset|length|style|BOLD|2222547|(重点是我的)。|2222548|即使您想要做的事情已经奏效(以编程方式替换源文件的编码)，它也没有任何意义。想想看:代码是静态的(不会改变)。尝试以不同的编码方式阅读它是没有意义的:只有一个正确的编码(源的作者在其中编辑源)。|2222549|至于语法：|2222550|#+This+Python+file+uses+the+following+encoding:+utf-8|code-block|syntax|javascript|2222551|PEP本身说，这种语法是“没有解释器行，使用纯文本”。它是为人类而放置的。这样，如果您在文本编辑器中打开一个文件并发现它充满了胡言乱语，您就可以在它的菜单中手动设置源代码。|2222552|编辑：为什么要把编码放在#+-*-和-*-之间。这纯粹是传统。第一个符号，哈希符号，告诉它是一个注释(所以它不会被编译成字节码)，然后_*_只是告诉解析器特定注释是给他/她的一种方式。|CODE|2222553|这和输入你的来源没有什么不同：|2222554|#+TODO:+fix+this+nasty+bug|2222555|其中，TODO:部分告诉开发人员(和一些IDE)，这是一条需要操作的消息。你可以用任何你想要的，包括@MarkZar或WTF!.只是个惯例！|2222556|哈哈！|2222557|entityMap^0|0|G|3|Q|3|0|0|0|0|0|0|0|3|C|5|I|3|1V|3|0|0|0|3|5|1E|8|1N|4|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|19|8|@$E|1A|F|1B|G|H]|$E|1C|F|1D|G|H]]|9|@]|A|$]]|$1|I|3|J|5|6|7|1E|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|1F|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1G|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|1H|8|@]|9|@]|A|$R|S]]|$1|T|3|U|5|6|7|1I|8|@]|9|@]|A|$]]|$1|V|3|W|5|6|7|1J|8|@$E|1K|F|1L|G|H]|$E|1M|F|1N|G|X]|$E|1O|F|1P|G|X]|$E|1Q|F|1R|G|X]]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1S|8|@]|9|@]|A|$]]|$1|10|3|11|5|Q|7|1T|8|@]|9|@]|A|$R|S]]|$1|12|3|13|5|6|7|1U|8|@$E|1V|F|1W|G|X]|$E|1X|F|1Y|G|X]|$E|1Z|F|20|G|X]]|9|@]|A|$]]|$1|14|3|15|5|6|7|21|8|@]|9|@]|A|$]]|$1|16|3|-4|5|6|7|22|8|@]|9|@]|A|$]]]|17|$]]

The abstract of the PEP you link really says it all:

<blockquote>
 This PEP proposes to introduce a syntax to declare the encoding of
 a Python source file. The encoding information is then used by the
 Python parser to interpret the file using the given encoding. Most
 notably this enhances the interpretation of Unicode literals in
 the source code and makes it possible to write Unicode literals
 using e.g. UTF-8 directly in an Unicode aware editor.
</blockquote>

(the emphasis is mine).

Even if what you wanted to do would have worked (replacing the encoding of the source file programmatically), it wouldn't have had any sense. Think about it: the code is static (doesn't change). It would make no sense to try to read it with different encoding: there is only one correct one (the one the author of the source edited the source in).

As for the syntax:

<pre><code># This Python file uses the following encoding: utf-8
</code></pre>

the PEP itself says that that syntax is "Without interpreter line, using plain text". It is placed there for humans. So that if you open a file in a text editor and find it full of gibberish, you can manually set the encode of the source in its menu.

EDIT: As for why you should put the encoding between <code># -*-</code> and <code>-*-</code>... That's purely conventional. The first symbol, the hash sign, tells that that is a comment (so it won't be compiled to bytecode), then the <code>_*_</code> is just a way to tell the parser that that specific comment is for him/her.

It is not any different than putting in your source:

<pre><code># TODO: fix this nasty bug
</code></pre>

in which the <code>TODO:</code> part tells the developer (and some IDE) that this is a message requiring an action. You could have really used whatever your wanted, including <code>@MarkZar</code> or <code>WTF!</code>... just convention!

HTH!

blocks|key|2222590|text|python编码声明的重要部分是coding:+utf-8，它应该在第一行python代码之前的注释中，您可以随意处理注释的另一部分。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2222591|以下是PEP中描述这种行为的行：|2222592|更准确地说，第一行或第二行必须匹配正则表达式"coding:=\s*(-\w.%2B)“。然后将该表达式的第一组解释为编码名称。如果Python不知道编码，则会在编译期间引发错误。在包含编码声明的行中不能有任何Python语句。|blockquote|2222593|entityMap^0|G|D|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|P|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Q|8|@]|D|@]|E|$]]|$1|K|3|-4|5|6|7|R|8|@]|D|@]|E|$]]]|L|$]]

The important part of python encoding declaration is <code>coding: utf-8</code> and it should be in a comment before the first line of python code, and you can do whatever you want with the other part of the comment.

Here is the lines in the PEP described this behaviour:

<blockquote>
 More precisely, the first or second line must match the regular
 expression "coding[:=]\s*([-\w.]+)". The first group of this
 expression is then interpreted as encoding name. If the encoding
 is unknown to Python, an error is raised during compilation. There
 must not be any Python statement on the line that contains the
 encoding declaration.
</blockquote>

blocks|key|2222599|text|使用行中任意位置的正则表达式coding[:=]\s*([-\w.]%2B)搜索编码设置。这意味着：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2222600|找到确切的字符串coding=或coding:，后面是零或多个空格字符，然后是至少一个字母数字、_或-字符的运行。|unordered-list-item|2222601|抓住至少一个..。|2222602|捕获的部分用作编码。|2222603|也就是说，使用以下内容是完全合法的|2222604|#+This+program+was+written+for+Python+3.+Encoding+that+should+be+used+for+decoding:+UTF-8!|code-block|syntax|javascript|2222605|因为所需格式的字符串仍然可以是在那里发现的。|2222606|Python3源文件默认为UTF-8作为编码，因此只要使用UTF-8，就不需要在Python3代码中使用#+coding:+utf-8。|BOLD|2222607|entityMap|0|LINK|mutability|MUTABLE|url|https://regex101.com/r/yBViO9/1^0|E|M|0|8|7|G|7|1C|1|1E|1|0|0|0|0|0|F|6|0|0|0|7|1G|F|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|I|3|J|5|H|7|1I|8|@]|D|@]|E|$]]|$1|K|3|L|5|H|7|1J|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1K|8|@]|D|@]|E|$]]|$1|O|3|P|5|Q|7|1L|8|@]|D|@]|E|$R|S]]|$1|T|3|U|5|6|7|1M|8|@]|D|@$9|1N|A|1O|1|1P]]|E|$]]|$1|V|3|W|5|6|7|1Q|8|@$9|1R|A|1S|B|X]|$9|1T|A|1U|B|C]]|D|@]|E|$]]|$1|Y|3|-4|5|6|7|1V|8|@]|D|@]|E|$]]]|Z|$10|$5|11|12|13|E|$14|15]]]]

The encoding setting is searched using the regular expression <code>coding[:=]\s*([-\w.]+)</code> anywhere on the line. This means:

<ul>
<li>find the exact string <code>coding=</code> or <code>coding:</code> followed by zero or more white-space characters, followed by a run of at least one character that are alphanumeric, <code>_</code> or <code>-</code>.</li>
<li>capture the run of at least one... </li>
<li>the captured part is used as the encoding.</li>
</ul>

That is, it is perfectly legal to use anything like

<pre><code># This program was written for Python 3. Encoding that should be used for decoding: UTF-8!
</code></pre>

because the string in required format can still be <a href="https://regex101.com/r/yBViO9/1" rel="nofollow noreferrer">found there</a>.

<hr>

Python 3 source files default to UTF-8 as the encoding, so no <code># coding: utf-8</code> is necessary in Python 3 code for as long as you use UTF-8.

I learned from the websitethat I should add the code declaration in python when i wan't to input friendly unicode characters: <a href="http://www.python.org/dev/peps/pep-0263/">http://www.python.org/dev/peps/pep-0263/</a>, but I still feel confused about it.

Assume that i work in linux with vim, and i create a new py file and input codes as follows:

<pre><code>#!/usr/bin/python2.7
# -*- coding: utf8 -*-
s = u'ޔ'
print s
</code></pre>

1. I tried to replace line 2 with codes as follows:

<pre><code>import sys
reload(sys)
sys.setdefaultencoding('utf8')
</code></pre>

but it doesn't work, aren't they same?

2. I am not very familiar with linux, I really dont know why should i add <code>_*_</code> at the beginning and end of code delcaration, and when i tried to replaced <code># -*- coding: utf8 -*-</code> with <code># code=utf8</code> or <code># code: utf8</code>, I got an error:

<pre><code>File "pythontest.py", line 3
SyntaxError: Non-ASCII character '\xde' in file pythontest.py on line 3, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details
</code></pre>

but these code declaration is mentioned in the website <a href="http://www.python.org/dev/peps/pep-0263/">http://www.python.org/dev/peps/pep-0263/</a>! 

and according to the documentation , the code declaration as follows is allowed:

<pre><code># This Python file uses the following encoding: utf-8
</code></pre>

Oops, what's this? I don't think it can be recognized by computer.what in the world should the code declared? I feel more and more confused.

Thanks for help.

what kind of encode declaration should I input in python

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我从网站上了解到，当我不想输入友好的unicode字符：时，我应该在python中添加代码声明，但我仍然对此感到困惑。假设我在linux中使用vim，然后创建一个新的py文件和输入代码，如下所示：#!/usr/bin/python2.7# -*- coding: utf8 -*-s = u'ޔ'print s1。我试图...

问我应该在python中输入什么样的代码声明？
EN

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问我应该在python中输入什么样的代码声明？EN