反斜杠转义在Python中不起作用

Question

I want Python interpreter to show me \\' as a calculated value. I tried typing "\\\\'" and it returned me the same thing. If I try "\\'" then the backslash is not shown anymore after I hit return. How do I get it to show the backslash like this after I hit return- \\' ?

Additional question

This is exact question I am not understanding: Expression -->

'C' + + 'D'

Calculated Value -->

'C\\'D'

Find the missing literal

Answer 1

Here are two ways to get \\' :

>>> print("\\'")
\'
>>> print(r"\'")
\'

Discussion

>>> print("\'")
'

The above prints out a single ' because an escaped ' is just a ' .

>>> print(r"\'")
\'

The above prints the backslash because r prevents interpretation of escapes.

>>> print("\\'")
\'

The above prints \\' because an escaped backslash is a backslash.

Other forms of strings

Using unicode-strings (under python2):

>>> print(u"\\'")
\'
>>> print(ur"\'")
\'

Using byte-codes (also python 2):

>>> print(b"\\'")
\'
>>> print(br"\'")
\'

Answer for additional question

Using the principles described above, the answer for the additional question is:

>>> print('C' + "\\'" 'D')
C\'D
>>> print('C' + r"\'" 'D')
C\'D

Answer 2

print("\\'")

repr of a string will never put out a single backslash. repr smartly picks quotes to avoid backslashes. You can get a \\' to come out if you do something like '\\'"'