Problem with RE matching backslash
__peter__ at web.de
Tue Jan 27 18:56:13 CET 2004
Jeff Epler wrote:
>> What is still not clear to me is why the search examples work and yield
> Because the first pattern, which you wrote as "\\m", will match a lone
> 'm'. So 'match' fails, because m is not in the first position. But
> 'search' succeeds at index 1.
This was my first guess, but it took me a while do find it documented.
I will reproduce the tiny relevant paragraph from
"The special sequences consist of "\" and a character from the list below.
If the ordinary character is not on the list, then the resulting RE will
match the second character. For example, \$ matches the character "$". "
[description of characters with special meaning omitted]
I don't know if this list of characters is likely to grow, but I would
definitely prefer a "bogus escape" exception:
<_sre.SRE_Pattern object at 0x40289660>
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/local/lib/python2.3/sre.py", line 179, in compile
return _compile(pattern, flags)
File "/usr/local/lib/python2.3/sre.py", line 229, in _compile
raise error, v # invalid expression
sre_constants.error: bogus escape: '\\1'
More information about the Python-list