python - 带有 re.search() 的原始字符串？

Question

我正在尝试学习如何使用 Python 正则表达式。我希望以下程序在输入字符串中搜索字符串 'N\S\A'。我读到 ( here ) 如果你想处理 '\' 字符，你必须将字符串设为原始字符串。但是我把 r 放在匹配字符串的前面，它仍然不起作用。 (不管inword是'NSA'还是'N\S\A'...)

import re
inword = input('Enter in text that may or may not be suspicious: ')
print("Inword is:", inword)
mword  = re.search(r'N\S\A',inword)
if mword :
    print('Matched',mword .group())
    #deployDrones();
else:
    print('Not matched')

为什么这不起作用？我该怎么做才能修复它？

Answer 1

你不需要正则表达式。

使用 in 运算符:

>>> inword = 'Hello N\S\A!'
>>> r'N\S\A' in inword
True

如果你真的需要正则表达式，你需要转义\本身，因为\S匹配非空格字符(\A也具有特殊意义):

>>> inword = 'Hello N\S\A!'
>>> re.search(r'N\S\A', inword)
>>> re.search(r'N\\S\\A', inword)
<_sre.SRE_Match object at 0x7f804ea33370>

\S

When the UNICODE flags is not specified, matches any non-whitespace character; this is equivalent to the set [^ \t\n\r\f\v] The LOCALE flag has no extra effect on non-whitespace match. If UNICODE is set, then any character not marked as space in the Unicode character properties database is matched.

\A

Matches only at the start of the string.

来自 Regular expression syntax