why \b doesn't work in python re module?

Question

It is known that \b means word boundary in regular expression. However the following code of re module in python doesn't work:

>>> p=re.compile('\baaa\b')
>>> p.findall("aaa vvv")
[]

I think the returned results of findall should be ["aaa"], however it didn't find anything. What's the matter?

(Single quotes disabling escapes isn’t a Python thing; the two types are equivalent.) — Ry-, Jan 12 '14 at 04:21

score 27 · Accepted Answer · answered Jan 12 '14 at 04:19

27

You need to use a raw string, or else the \b is interpreted as a string escape. Use r'\baaa\b'. (Alternatively, you can write '\\b', but that is much more awkward for longer regexes.)

answered Jan 12 '14 at 04:19

BrenBarn

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I got it. Thank you for the timely answer! – user2384994 Jan 12 '14 at 04:21

why \b doesn't work in python re module?

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