regex support

regex support

[Ryan Bowman]

Does emacs support the regex syntax {4} or any of it's
variants?  I'd like to match a date a la 2005-04-19,
so I'm trying (for the year part) something like
"[0-9]{4}", but unless I'm doing something wrong it
doesn't seem to be working.  Assuming it doesn't
support that, is there a better way to match an string
of digits of length 4 than "[0-9][0-9][0-9][0-9]"?

----
Ryan Bowman

While any text editor can save your files, only Emacs can save your soul. -- Per Abrahamsen

Emacs is not built by hate of vi. vi is irrelevant - it is no more than a strange punishment that the unbelievers submit themselves to. -- Matan Ninio
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Re: regex support

[Daniel Wright]

Ryan Bowman <ryanlbowman@yahoo.com> writes:

> Does emacs support the regex syntax {4} or any of it's
> variants?  I'd like to match a date a la 2005-04-19,
> so I'm trying (for the year part) something like
> "[0-9]{4}", but unless I'm doing something wrong it
> doesn't seem to be working.  Assuming it doesn't
> support that, is there a better way to match an string
> of digits of length 4 than "[0-9][0-9][0-9][0-9]"?

You need a couple of extra backslashes, try "[0-9]\{4\}".

There's a full description in the "regexps" node of the emacs info:

(info "(emacs)regexps");<--- hit C-x C-e here.

Greetings,
Daniel.

Re: regex support

[Peter Dyballa]

Am 28.04.2005 um 23:29 schrieb Ryan Bowman:

> so I'm trying (for the year part) something like "[0-9]{4}"

This should work: "[0-9]\{4\}" -- and this too: C-h i m Emacs RET m 
Regexps RET.

--
Greetings

   Pete

The human brain operates at only 10% of its capacity. The rest is 
overhead for the operating system.

Re: regex support

[Llewelly]

Ryan Bowman <ryanlbowman@yahoo.com> writes:

> Does emacs support the regex syntax {4} or any of it's
> variants?

Yes. See C-h i g (emacs)Regexps

However you need to put a backslash before the curly braces:

\{4]\} instead of {4}

> I'd like to match a date a la 2005-04-19,
> so I'm trying (for the year part) something like
> "[0-9]{4}", but unless I'm doing something wrong it

"[0-9]\\{4\\}-[0-9]\\{2\\}-[0-9]\\{2\\}"

should do the trick. Note I used double backslashes (\\) within the
string. If your regex isn't in a string literal use single backslash
(\) .

> doesn't seem to be working.  Assuming it doesn't
> support that, is there a better way to match an string
> of digits of length 4 than "[0-9][0-9][0-9][0-9]"?
[snip]

hm... "[0-9]\\{4\\}" is fewer chars but "[0-9][0-9][0-9][0-9]" is
easier to read ...