Re: is expr's \? regex metachar working?

[Andreas Schwab]

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.

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