strip() 方法不适用于 str 类

Question

First, I have bytes class object "myst". I then convert it to a str class using str() , and remove the whitespace using the strip() method. The problem is that the whitespace "\\r\\n" is not removed.

>>> myteststring=b'asdf\r\n'
>>> str(myteststring)
"b'asdf\\r\\n'"
>>> str(myteststring).strip()
"b'asdf\\r\\n'"

But, using the strip() method on a byte class works properly.

>>> byteclass=b'asdf\r\n'
>>> byteclass.strip()
b'asdf'

What's wrong here?

---

I think when I use str() , the resulting string includes double back slash \\\\ . This is may be root of my problem.

>>> myteststring
b'asdf\r\n'
>>> str(myteststring)
"b'asdf\\r\\n'"   # << this is problem ??

Answer 1

When passed a bytes object without an encoding argument, the str function would simply call the repr function to return the string representation of the given bytes object, which is why str(myteststring) returns "b'asdf\\\\r\\\\n'" , with \\r\\n escaped with additional backslashes.

You can properly convert a bytes object to a string by passing to the str function an encoding argument instead:

>>> myteststring=b'asdf\r\n'
>>> str(myteststring, encoding='utf-8')
'asdf\r\n'
>>> str(myteststring, encoding='utf-8').strip()
'asdf'