[Tutor] regular expression matching a dot?
kent37 at tds.net
Wed Oct 19 12:08:11 CEST 2005
Christian Meesters wrote:
> I've got the problem that I need to find a certain group of file names
> within a lot of different file names. Those I want to match with a
> regular expression are a bit peculiar since they all look like:
> 07SS.INF , 10SE.INF, 13SS.INF, 02BS.INF, 05SS.INF.
> Unfortunately there are similar file names that shouldn't be matched,
> 01BE.INF, 02BS.INF
> Any other extension than 'INF' should also be skipped. (There are names
> like 07SS.E00, wich I don't want to see matched.)
> So I tried the following pattern (using re):
> \d+[SS|SE]\.INF - as there should be at least one digit, the group 'SE'
> or 'SS' followed by a dot and the extension 'INF'.
Use parentheses () for grouping. Brackets  define a group of characters. Your re says to match
\d+ one or more digits
[SS|SE] exactly one of the characters S, |, E
\.INF literal .INF
Since there are TWO characters S or E, nothing matches. Change the  to () and it works.
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