Regex for finding value inside parenthesis

Question

I have a line of code:

<link href="<%= Page.ResolveClientUrl("~/Styles/CAR.css") %>" rel="stylesheet" type="text/css" />

I just want to extract ~/Styles/CAR.css from it. Kindly let me know Regex for this. link href tag may contain other syntax as well to refer css. For Ex, <link href="<%= Url.Content("~/Styles/CAR.css") %>" rel="stylesheet" type="text/css" />

I have a line of code: " rel="stylesheet" type="text/css" /> I just want to extract "~/Styles/CAR.css" from it. Kindly let me know Regex for this. link href tag may contain other syntax as well to refer css. For Ex, " rel="stylesheet" type="text/css" /> — Kabir, Jan 27 '14 at 13:07
I was under the impression that bad things happen when you try to parse html with regex... http://stackoverflow.com/a/1732454/24908 =) — Aaron Palmer, Jan 27 '14 at 13:24
`Page.ResolveClientUrl` and `Url.Content` don't necessarily result in the same output, so how would this be reliable? Why don't you parse the generated HTML instead of server-side code? — nmclean, Jan 27 '14 at 13:33

Sergey Berezovskiy · Answer 1 · 2014-01-27T13:17:07.580

I suggest you to use HtmlAgilityPack (available from NuGet) for HTML parsing. Getting href attribute value will look like:

HtmlDocument doc = new HtmlDocument();
doc.LoadHtml(stringWithHtml);
var link = doc.DocumentNode.SelectSingleNode("//link[@href]");
var href = link.Attributes["href"].Value;

Then you can extract ~/Styles/CAR.css from content of attribute. Regex is good here, but you also can avoid it:

int startIndex = href.IndexOf('"');
int endIndex = href.LastIndexOf('"');
var result = href.Substring(startIndex + 1, endIndex - startIndex - 1);
// ~/Styles/CAR.css

Extracting path with regex will look like

var match = Regex.Match(href, @"ResolveClientUrl\(""(.*)""\)");
if (match.Success)
    result = match.Groups[1].Value;

score 1 · Accepted Answer · edited May 23 '17 at 10:31

1

Besides that you should'nt parse HTML with regex, I'd go for

\(\"(.+)\"\)

as your regex. Simply extract anything between (" and ").

For example:

string strRegex = @"\(\""(.+)\""\)";
Regex myRegex = new Regex(strRegex, RegexOptions.None);
string strTargetString = @"<link href=""<%= Page.ResolveClientUrl(""~/Styles/CAR.css"") %>"" rel=""stylesheet"" type=""text/css"" />";

foreach (Match myMatch in myRegex.Matches(strTargetString))
{
  if (myMatch.Success)
  {
    // Add your code here
  }
}

(example code taken from http://regexhero.net/tester/)

If there will be only one occurence of <link href=""<%= Page.ResolveClientUrl(""~/Styles/CAR.css"") %>"" rel=""stylesheet"" type=""text/css"" /> or you want to get only the first occurence, then you can get rid of the for-loop and use:

string strRegex = @"\(\""(.+)\""\)";
Regex myRegex = new Regex(strRegex, RegexOptions.None);
string strTargetString = @"<link href=""<%= Page.ResolveClientUrl(""~/Styles/CAR.css"") %>"" rel=""stylesheet"" type=""text/css"" />";

Match myMatch = myRegex.Match(strTargetString);

The difference here is using Regex.Matches(string) (which returns a MatchCollection; every matched occurence) vs Regex.Match(string) (which returns a single Match; the first matched occurence only).

edited May 23 '17 at 10:31

Community

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1

answered Jan 27 '14 at 13:24

KeyNone

8,745
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I dont want to use foreach loop here. Is there anything, where I can assign "myRegex.Matches(strTargetString))" value to "myMatch" directly. When I am using "Match myMatch = myRegex.Matches(strTargetString);", I am getting null value in myMatch. – Kabir Jan 28 '14 at 11:42
@Kanaiya well `Matches(string)` returns a [`MatchCollection`](http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.matchcollection.aspx), so every match. If you only want one single match, use [`Match(string)`](http://msdn.microsoft.com/en-us/library/twcw2f1c.aspx), this will return the first occurence (if any). If there is only one occurence of ` – KeyNone Jan 28 '14 at 12:31
Thanks a lot. That works, But i GET {("~/Styles/CAR.css")}. I just need ~/Styles/CAR.css to get extracted. I tried editing your Regex, but still, i am unable to get desirable output. Pls let me know the Regex to get output value. – Kabir Jan 29 '14 at 06:12
@Kanaiya most likely this is NOT a problem with the regex. The **whole match** is `("~/Styles/CAR.css")` since we _match_ on `("` and `")`, too! You only want to extract the first [capturing group](http://www.regular-expressions.info/brackets.html) only! This could be done with `myMatch.Groups[1].Value` (but be careful: the [Groups](http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.match.groups.aspx)-property won't have two (or more) members when the regex fails to match!) – KeyNone Jan 29 '14 at 08:37

score 0 · Answer 3 · answered Jan 27 '14 at 13:11

0

use this:

/\(([^\)]*)\)/

Tested with perl:

> cat temp
<link href="<%= Page.ResolveClientUrl("~/Styles/CAR.css") %>" rel="stylesheet" type="text/css" />
> perl -lne 'print $1 if(/\(([^\)]*)\)/)' temp
"~/Styles/CAR.css"
>

answered Jan 27 '14 at 13:11

Vijay

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NavyCody · Answer 4 · 2014-01-27T13:26:38.517

For quick regex we can use the information inside the quotes inside parentheses (("~/Styles/CAR.css") ) and use that info to group it into one one.

Escaping the parentheses one quick regex would be

In the above regex there are two groups. The first matched group would give us the required information i.e. ~/Styles/CAR.css.

You can check it in http://regexpal.com/ and experiment with other patterns.

Regex for finding value inside parenthesis

4 Answers4