How do I determine the file extension of a file name string?
lets say I have
I'm.a.file.name.tXt
the regex should return tXt
A:
/^(.*?)\.(.*)$/
The '?' makes it greedy. Your result will be in the second group.
Thomas O
2010-07-20 17:18:45
I'm, and a.file.name.tXt not just tXt
DerNalia
2010-07-20 17:21:22
In which case remove the greedy match at put it on the second group.You said you only wanted 'tXt'.
Thomas O
2010-07-20 17:22:15
The `?` makes a quantifier **lazy**, *not* greedy!
Peter Boughton
2010-07-20 17:27:53
Based on your comment, you possibly misunderstand greedy vs lazy matching. Read more at http://www.regular-expressions.info/repeat.html but basically, if taking this approach, you want `(greedy).(lazy)` in order to consume as much as possible for the first group and as little as required for the second.
Peter Boughton
2010-07-20 17:35:44
As an extension, you possibly want make to the `\.` a lookbehind - so `(?<=\.)[^.]*$` - to avoid potentially having to remove the `.` later. Though not all regex implementations support lookbehinds, and we don't know what one this is for.
Peter Boughton
2010-07-20 17:33:55
A:
What language is this in? It's quite possible you don't want to actually use a regex - assuming the name is a String you'll probably just want to do something like split it over periods and then choose the last segment. Okay, that's sort of a regex answer, but not a proper one.
Stephen
2010-07-20 17:20:20
+1
A:
You probably don't need regex - most languages will have the equivalent to this:
ListLast(Filename,'.')
(If you do need regex for some reason, Scharron's answer is correct.)
Peter Boughton
2010-07-20 17:25:18