如何通过使用python匹配特定的字符串

Question

I want to print the string. In my code i am not getting the right string.

line="\\python\001tag\file.txt"  
str=re.search(r"\[(0-9)+]",line)   (don't use raw_string here)

print str.group()

This gives nothing. I want to extract 001 from there.

Note: I don't want to use rawstring.because here user is getting the path from other resource. Is it possible to replace single slash by double slash to solve this problem

Answer 1

You need to use a raw-string so that escape sequences are not processed:

sat = r"\\Python\001tag\file.txt"

Demo:

>>> sat = r"\\Python\001tag\file.txt"
>>> sat
'\\\\Python\\001tag\\file.txt'
>>> print(sat)
\\Python\001tag\file.txt
>>>

Answer 2

Three errors: '\\001' gives the codepoint in octal, actually the character at codepoint 1. Use double \\\\ or raw-strings. Second: r'\\[' escapes the '[', use double \\\\ instead: r'\\\\[+0-9()]' (I have rearranged the characters in the set, so that it doesn't look like a expression group. Third: You want to look at str.group(0) to get the whole matched string.