re.match failed to match left square brackets as the first char

[boqu]

BPO	29959
Nosy	@ezio-melotti, @serhiy-storchaka

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2017-04-01.07:44:16.345>
created_at = <Date 2017-04-01.07:38:49.820>
labels = ['expert-regex', 'type-bug', 'invalid']
title = 're.match failed to match left square brackets as the first char'
updated_at = <Date 2017-04-05.06:19:52.816>
user = 'https://bugs.python.org/boqu'

bugs.python.org fields:

activity = <Date 2017-04-05.06:19:52.816>
actor = 'bo qu'
assignee = 'none'
closed = True
closed_date = <Date 2017-04-01.07:44:16.345>
closer = 'serhiy.storchaka'
components = ['Regular Expressions']
creation = <Date 2017-04-01.07:38:49.820>
creator = 'bo qu'
dependencies = []
files = []
hgrepos = []
issue_num = 29959
keywords = []
message_count = 3.0
messages = ['290968', '290969', '291158']
nosy_count = 4.0
nosy_names = ['ezio.melotti', 'mrabarnett', 'serhiy.storchaka', 'bo qu']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29959'
versions = ['Python 3.5']

[boqu]

if "[" is the first char in a string, then re.match can't match any pattern from the string, but re.findall works fine

details as follows:

[da@namenode log]$ python3
Python 3.4.3 (default, Jun 14 2015, 14:23:40) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-11)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> cyzd="[abc]"
>>> cyzd
'[abc]'
>>> pattern="ab(.*)"
>>> pattern
'ab(.*)'
>>> match=re.match(pattern, cyzd)
>>> match
>>> pattern=r'ab(.*)'     
>>> re.findall(pattern, cyzd)
['c]']

[serhiy-storchaka]

re.match() checks if the beginning of the string matches the regular expression pattern. Use re.search() if you want to find the match not at the beginning of the string.

https://docs.python.org/3/library/re.html#re.match
https://docs.python.org/3/library/re.html#re.search

[boqu]

hi Serhiy Storchaka
thank you for your explanation, it helps a lot

2017-04-01 15:44 GMT+08:00 Serhiy Storchaka <report@bugs.python.org>:

Serhiy Storchaka added the comment:

re.match() checks if the beginning of the string matches the regular
expression pattern. Use re.search() if you want to find the match not at
the beginning of the string.

https://docs.python.org/3/library/re.html#re.match
https://docs.python.org/3/library/re.html#re.search

----------
nosy: +serhiy.storchaka
resolution: -> not a bug
stage: -> resolved
status: open -> closed

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Python tracker <report@bugs.python.org>
<http://bugs.python.org/issue29959\>

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