encode / decode之间有什么区别？ [英] What is the difference between encode/decode?

问题描述

我从来没有确定我理解了str / unicode decode和encode之间的区别。

I've never been sure that I understand the difference between str/unicode decode and encode.

我知道 str（）。 decode（）用于当你有一个字符串的字符串，你知道有一定的字符编码，给定编码名称，它将返回一个unicode字符串。

I know that str().decode() is for when you have a string of bytes that you know has a certain character encoding, given that encoding name it will return a unicode string.

我知道 unicode（）。encode（）根据给定的编码名称将unicode chars转换为字节字符串。

I know that unicode().encode() converts unicode chars into a string of bytes according to a given encoding name.

但我不明白 str（）。encode（）和 unicode code>为。

But I don't understand what str().encode() and unicode().decode() are for. Can anyone explain, and possibly also correct anything else I've gotten wrong above?

编辑：

有几种方法可以解决上述问题答案给出了关于字符串上 .encode 的信息，但没有人似乎知道 .decode unicode。

Several answers give info on what .encode does on a string, but no-one seems to know what .decode does for unicode.

推荐答案

unicode字符串的 decode 方法有任何应用程序（除非你有一些非文本数据在unicode字符串由于某种原因 - 见下文）。它主要是因为历史原因，我想。在Python 3中它完全消失了。

The decode method of unicode strings really doesn't have any applications at all (unless you have some non-text data in a unicode string for some reason -- see below). It is mainly there for historical reasons, i think. In Python 3 it is completely gone.

unicode（）。decode（）使用默认（ascii）编解码器编码 s 的。验证方法如下：

unicode().decode() will perform an implicit encoding of s using the default (ascii) codec. Verify this like so:

>>> s = u'ö'
>>> s.decode()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'\xf6' in position 0:
ordinal not in range(128)

>>> s.encode('ascii')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'\xf6' in position 0:
ordinal not in range(128)

错误讯息完全相同。

对于 str （）这是另一种方法 - 它尝试使用默认编码的 s 的隐式解码 p>

For str().encode() it's the other way around -- it attempts an implicit decoding of s with the default encoding:

>>> s = 'ö'
>>> s.decode('utf-8')
u'\xf6'
>>> s.encode()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 0:
ordinal not in range(128)

这样使用， str（）。encode（）也是多余的。

Used like this, str().encode() is also superfluous.

但有另一个应用程序的后一种方法是有用的：编码与字符集无关，因此可以以有意义的方式应用于8位字符串：

But there is another application of the latter method that is useful: there are encodings that have nothing to do with character sets, and thus can be applied to 8-bit strings in a meaningful way:

>>> s.encode('zip')
'x\x9c;\xbc\r\x00\x02>\x01z'

你是对的，但是：这两个应用程序的编码模糊使用是... awkard。再次，在Python 3中使用单独的 byte 和 string 类型，这不再是一个问题。

You are right, though: the ambiguous usage of "encoding" for both these applications is... awkard. Again, with separate byte and string types in Python 3, this is no longer an issue.

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