Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!ames!lll-winken!uunet!yale!Duchier-Denys
From: Duchier-Denys@cs.yale.edu (Denys Duchier)
Newsgroups: comp.emacs
Subject: Re: Lisp Programming: Substring Searches, etc.
Message-ID: <65906@yale-celray.yale.UUCP>
Date: 10 Jul 89 00:16:19 GMT
References: <397@lxn.eds.com> <65891@yale-celray.yale.UUCP> <SPENCER.89Jul9162408@spline.eecs.umich.edu>
Sender: root@yale.UUCP
Reply-To: Duchier-Denys@cs.yale.edu (Denys Duchier)
Organization: Computer Science, Yale University, New Haven, CT 06520-2158
Lines: 20
In-reply-to: spencer@eecs.umich.edu (Spencer W. Thomas)

In article <SPENCER.89Jul9162408@spline.eecs.umich.edu>, spencer@eecs (Spencer W. Thomas) writes:
> In article <65891@yale-celray.yale.UUCP> Duchier-Denys@cs.yale.edu (Denys Duchier) writes:
>    (defun extract-file-extension (filename)
>      (and (string-match ".+\\.\\(.*\\)$" filename)
> 	  (substring filename (match-beginning 1) (match-end 1))))
> 
> Actually, probably better would be
> 	 (string-match ".+\\.\\([^.]*\\)$" filename)
> This pattern will match the last ".", while the given pattern will
> match the first one.
> 
> --
> =Spencer (spencer@eecs.umich.edu)

Wrong, .+ eats up as much of the string as possible. The version you
propose can be simplified to "\\.\\([^.]*\\)$", but I rejected it when
I wrote the proposed solution because I didn't want files like .login
to be mistaken for files with an empty name and just an extension.

--Denys