原因：python字符串赋值意外地将'\\ b'更改为'\\ x08'而将'\\ a'更改为'\\ x07'，为什么Python会这样做？

Question

Had two answers and some comments, mentioned another question, but all had not provided REASON, why Python did this changes? such as '/b' is '/x08' is just the result, but why? Cheers.

I try to add this path"F:\\big data\\Python_coding\\diveintopython-5.4\\py" into sys.path, therefore, the code under it could be imported directly.

after using : sys.path.append('F:\\big data\\Python_coding\\diveintopython-5.4\\py')

I found I had this path inside sys.path: 'F:\\x08ig data\\Python_coding\\diveintopython-5.4\\py'

I then tested using the following code: mypath1='F:\\big data\\bython_coding\\aiveintopython-5.4\\ry'

the mypath1 now is : 'F:\\x08ig data\\x08ython_coding\\x07iveintopython-5.4\\ry'

all the '\\b' changed into '\\x08' and '\\a' changed into '\\x07'

I searched for a while, but still can not find the reason, could you please check it out and any feedback or help will be appropriated. Many thanks.

Answer 1

Your strings are being escaped. Check out the docs on string literals :

The backslash () character is used to escape characters that otherwise have a special meaning, such as newline, backslash itself, or the quote character. String literals may optionally be prefixed with a letter r' or R'; such strings are called raw strings and use different rules for backslash escape sequences.

This is a historical usage dating from the early 60s. It allows you to enter characters that you're not otherwise able to enter from a standard keyboard. For example, if you type into the Python interpreter:

print "\xDC"

...you'll get Ü . In your case, you have \\b - representing backspace - which Python displays in the \\xhh form, where hh is the hexadecimal value for 08. \\a is the escape sequence for the ASCII bell: try print "\\a" with your sound on and you should hear a beep.

Answer 2

Escape sequence \\a , \\b is equivalnt to \\x07 , \\x08 .

>>> '\a'
'\x07'
>>> '\b'
'\x08'

You should escape \\ itself to represent backslash literally:

>>> '\\a'
'\\a'
>>> '\\b'
'\\b'

or use raw string literals:

>>> r'\a'
'\\a'
>>> r'\b'
'\\b'