Re: [Boost-Users] Inconsistent regexp matching when using quantifiers?

From: John Maddock (john_maddock_at_[hidden])
Date: 2003-04-26 07:15:23

> I'm using regexp from boost-1.28 and experience the following
> behavior.  Consider the following (somewhat artificial) regexp
> pattern:
>
> a{1}b
>
> As I expected, that pattern is found in "ab" but not "aab".
>
> To my suprise however, the same pattern *is* found
> in "aaab", "aaaaab", and any other string consisting of an odd number
> of "a"s followed by a "b".  It is not found in strings consisting of
> an even number of "a"s followed by a "b".  This seems odd (no pun
> intended).
>
> I see the same sort of behavior with quantifiers other than "{1}" and
> where the quantified expression matches other single characters.
> (Oddly enough, the behavior changes when using a quantified
> expression that matches multiple characters.  "(ab){1}c" is found
> in "abc", "ababc", "abababc", and any other string containing "abc".)

I can verify that - I'll try and get it fixed in the next version as it is a
very definite bug :-(

Thanks for reporting that one,

John Maddock.