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RegEx search for a substring within a substring

How can I use regular expressions to search for a substring within
another substring? For example, if I have the string:

"This is * some text <button id="123">Some * text</button>"

and I only wanted to find the * character(s) that appear within the
<button> tags, how could I do that using reg ex?

Thanks in advance for the help.

Nov 17 '05 #1
3 2308
co*********@gma il.com wrote:
How can I use regular expressions to search for a substring within
another substring? For example, if I have the string:

"This is * some text <button id="123">Some * text</button>"

and I only wanted to find the * character(s) that appear within the
<button> tags, how could I do that using reg ex?


You'll need to write a regular expression that uses balanced matching,
to make sure that any given * is actually within the scope defined by
the button tag. Have a look at this blog article for information on
balanced matching:

http://blogs.msdn.com/bclteam/archiv...15/396452.aspx
Oliver Sturm
--
omnibus ex nihilo ducendis sufficit unum
Spaces inserted to prevent google email destruction:
MSN oliver @ sturmnet.org Jabber sturm @ amessage.de
ICQ 27142619 http://www.sturmnet.org/blog
Nov 17 '05 #2
Oliver Sturm wrote:
You'll need to write a regular expression that uses balanced matching,
to make sure that any given * is actually within the scope defined by
the button tag.


Or, thinking about it, you don't want to do that at all, because the
button tag can't be nested at all. In that case, try something like this:

<button[^>]*>(.*?(?<asteri sk>\*).*?)*</button>

Oliver Sturm
--
omnibus ex nihilo ducendis sufficit unum
Spaces inserted to prevent google email destruction:
MSN oliver @ sturmnet.org Jabber sturm @ amessage.de
ICQ 27142619 http://www.sturmnet.org/blog
Nov 17 '05 #3
co*********@gma il.com writes:
How can I use regular expressions to search for a substring within
another substring? For example, if I have the string:

"This is * some text <button id="123">Some * text</button>"

and I only wanted to find the * character(s) that appear within the
<button> tags, how could I do that using reg ex?

Thanks in advance for the help.


Are you trying to parse HTML, SGML, XML, or some other markup language
using regular expressions? If so, the Perl FAQ will tell you why that's
a bad idea. Use a parser for parsing.

Also - why the cross-post? Regular expressions are not generic - so an
answer you get from the Perl group won't necessarily apply to a regex
engine that's written in C#, and vice versa. If you have a question about
C# regexes, ask it in the C# group.

sherm--

--
Cocoa programming in Perl: http://camelbones.sourceforge.net
Hire me! My resume: http://www.dot-app.org
Nov 17 '05 #4

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