如何在Python 3中在字节和字符串之间转换？ [英] How to convert between bytes and strings in Python 3?

问题描述

这是一个Python 101类型的问题，但是当我尝试使用一个似乎将我的字符串输入转换为字节的包时，让我感到困惑。

This is a Python 101 type question, but it had me baffled for a while when I tried to use a package that seemed to convert my string input into bytes.

您会在下面看到我自己找到的答案，但是我觉得这里值得记录，因为我花了很多时间来发掘正在发生的事情。它似乎是Python 3的通用名称，因此我没有提到我正在使用的原始程序包。这似乎不是一个错误（只是特定的程序包具有 .tostring（）方法，显然不是会产生我理解的方法一个字符串...）

As you will see below I found the answer for myself, but I felt it was worth recording here because of the time it took me to unearth what was going on. It seems to be generic to Python 3, so I have not referred to the original package I was playing with; it does not seem to be an error (just that the particular package had a .tostring() method that was clearly not producing what I understood as a string...)

我的测试程序如下：

import mangler                                 # spoof package

stringThing = """
<Doc>
    <Greeting>Hello World</Greeting>
    <Greeting>你好</Greeting>
</Doc>
"""

# print out the input
print('This is the string input:')
print(stringThing)

# now make the string into bytes
bytesThing = mangler.tostring(stringThing)    # pseudo-code again

# now print it out
print('\nThis is the bytes output:')
print(bytesThing)

此代码的输出给出以下内容：

The output from this code gives this:

This is the string input:

<Doc>
    <Greeting>Hello World</Greeting>
    <Greeting>你好</Greeting>
</Doc>


This is the bytes output:
b'\n<Doc>\n    <Greeting>Hello World</Greeting>\n    <Greeting>\xe4\xbd\xa0\xe5\xa5\xbd</Greeting>\n</Doc>\n'

因此，需要能够在字节和字符串之间进行转换，以避免最终将非ascii字符转换为gobbledegook。

So, there is a need to be able to convert between bytes and strings, to avoid ending up with non-ascii characters being turned into gobbledegook.

推荐答案

上述代码示例中的 mangler正在执行以下操作：

The 'mangler' in the above code sample was doing the equivalent of this:

bytesThing = stringThing.encode(encoding='UTF-8')

还有其他方式可以编写此代码（特别是使用 bytes（stringThing，encoding ='UTF-8'），但是上面的语法可以很清楚地知道发生了什么，并且恢复字符串的操作：

There are other ways to write this (notably using bytes(stringThing, encoding='UTF-8'), but the above syntax makes it obvious what is going on, and also what to do to recover the string:

newStringThing = bytesThing.decode(encoding='UTF-8')

这样做时，将恢复原始字符串。

When we do this, the original string is recovered.

注意，使用 str（bytesThing）只会转录所有gobbledegook，而无需将其转换回Unicode，除非您特别要求使用UTF-8，即 str（ bytesThing，encoding ='UTF-8'）。如果未指定编码，则不会报告错误。

Note, using str(bytesThing) just transcribes all the gobbledegook without converting it back into Unicode, unless you specifically request UTF-8, viz., str(bytesThing, encoding='UTF-8'). No error is reported if the encoding is not specified.

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