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Re: is expr's \? regex metachar working?
From: |
Andreas Schwab |
Subject: |
Re: is expr's \? regex metachar working? |
Date: |
23 Aug 2001 17:05:46 +0200 |
User-agent: |
Gnus/5.090003 (Oort Gnus v0.03) Emacs/21.0.105 |
Clark Morgan <address@hidden> writes:
|> On Thu, Aug 23, 2001 at 04:47:31PM +0200, Andreas Schwab wrote:
|> > ???? The regexp _is_ matching, since expr prints > 0.
|>
|> $ ./expr "abcdef" : '.*b'
|> 2
|> $ ./expr "abcdef" : '.*b\+'
|> 2
|> $ ./expr "abcdef" : '.*b\?'
|> 6
|>
|> Does this illustrate why I think it's broken?
No, not at all.
|> Remember, the docu says: 0 or 1 matches. It seems to me that \?
|> matches 0 occurrences always.
Be carefull with such a statement, you have to check *all* cases, but a
single couterexample is enough to prove the opposite:
$ expr "abcdef" : 'a\?bcd'
4
You can only look at a regexp as a whole, context matters.
Andreas.
--
Andreas Schwab "And now for something
SuSE Labs completely different."
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- is expr's \? regex metachar working?, Clark O. Morgan, 2001/08/23
- Re: is expr's \? regex metachar working?, Andreas Schwab, 2001/08/23
- Re: is expr's \? regex metachar working?, Clark Morgan, 2001/08/23
- Re: is expr's \? regex metachar working?, Andreas Schwab, 2001/08/23
- Re: is expr's \? regex metachar working?, Clark Morgan, 2001/08/23
- Re: is expr's \? regex metachar working?,
Andreas Schwab <=
- Re: is expr's \? regex metachar working?, Clark Morgan, 2001/08/23
- Re: is expr's \? regex metachar working?, Andreas Schwab, 2001/08/23
- Re: is expr's \? regex metachar working?, Clark Morgan, 2001/08/23
- Re: is expr's \? regex metachar working?, Paul Jarc, 2001/08/23
Re: is expr's \? regex metachar working?, Clark O. Morgan, 2001/08/23