CODEWITHSUNDEEP
pythonregex
Nikhil
Nikhil

Reputation: 11

Python pattern matching issue

I have following two strings

root = 'svn\\456'
dir = 'svn\\456\\765'

pattern = re.compile('^'+root)
matched = pattern.match(dir)

I always get matched None. But if I do like following

root = 'svn\\456'
dir = 'svn\456\\765'

pattern = re.compile('^'+root)
matched = pattern.match(dir)

I get matched as True.

sorry if its a really basic thing which I am missing here. But I am just starting with python.

Thanks.

Upvotes: 1

Views: 53

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627607

You have a literal string that you are trying to use to create a regex object. It contains a special regex character that must be escaped.

You need to use re.escape function for that.

Here is an IDEONE demo:

import re
root = r'svn\456'
dir = r'svn\456\765'

pattern = re.compile('^'+re.escape(root))
matched = pattern.match(dir)
print(matched)

Upvotes: 0

Nir Alfasi
Nir Alfasi

Reputation: 53565

The problem with using 'svn\\456' as a pattern is that \ is a special character that requires escaping, so if you'll change the first pattern to: 'svn\\\\456' you'll get a match:

import re
root = 'svn\\\\456'
dir = 'svn\\456\\765'

pattern = re.compile('^'+root)
matched = pattern.match(dir) # matched!

Upvotes: 1

Related Questions