Regular expression of empty string

[ST Wong]

Hi all,

As metacharaters ^ and $ are not used in regular expression in XML,
I'm looking for how to specify empty string.

Would anyone please help?
Thanks a lot.
Regards,
ST Wong

[Richard Tobin]

In article <28**************************@posting.google.com >,
ST Wong <st*****@alumni.cuhk.net> wrote:

As metacharaters ^ and $ are not used in regular expression in XML,
I'm looking for how to specify empty string.

Assuming you mean XML Schema regular expressions, the empty regular
expression matches only the empty string.

-- Richard

[ST Wong]

ri*****@cogsci.ed.ac.uk (Richard Tobin) wrote in message news:<c5***********@pc-news.cogsci.ed.ac.uk>...

In article <28**************************@posting.google.com >,
ST Wong <st*****@alumni.cuhk.net> wrote:

As metacharaters ^ and $ are not used in regular expression in XML,
I'm looking for how to specify empty string.

Assuming you mean XML Schema regular expressions, the empty regular
expression matches only the empty string.

-- Richard

Thanks.

BTW, I've an xml file contains patterns for matching strings. It's
okay to match non-null strings by specifying the regular expression in
this way:

<data>.+</data>

But failed to match null string if I specify something like this:

<data></data>

Would you pls help?
I'm new to XML and sorry for the naive question.

Thanks again.
Sincerely,
ST Wong

[Richard Tobin]

In article <28**************************@posting.google.com >,
ST Wong <st*****@alumni.cuhk.net> wrote:

BTW, I've an xml file contains patterns for matching strings. It's
okay to match non-null strings by specifying the regular expression in
this way:

<data>.+</data>

But failed to match null string if I specify something like this:

<data></data>

Would you pls help?

You haven't told us what program it is that is using these regular
expressions. XML itself doesn't say anything about regular
expressions.

-- Richard

[ST Wong]

ri*****@cogsci.ed.ac.uk (Richard Tobin) wrote in message news:<c5**********@pc-news.cogsci.ed.ac.uk>...

In article <28**************************@posting.google.com >,
ST Wong <st*****@alumni.cuhk.net> wrote:

BTW, I've an xml file contains patterns for matching strings. It's
okay to match non-null strings by specifying the regular expression in
this way:

<data>.+</data>

But failed to match null string if I specify something like this:

<data></data>

Would you pls help?

You haven't told us what program it is that is using these regular
expressions. XML itself doesn't say anything about regular
expressions.

-- Richard

The file is used by Java programs.

Sorry for missing such important information.

Thanks again.
/ST

[Richard Tobin]

In article <28**************************@posting.google.com >,
ST Wong <st*****@alumni.cuhk.net> wrote:

The file is used by Java programs.

I think you need to refer to the Java regular expression
documentation, rather than XML.

-- Richard