Match and replace string in text using regular expressions

Question

I have a large string and it might have the following:

<div id="Specs" class="plinks">
<div id="Specs" class="plinks2">
<div id="Specs" class="sdfsf">
<div id="Specs" class="ANY-OTHER_NAME">

How can I replace values in the string from anything above to:

<div id="Specs" class="">

this is what I came up with, but it does not work:

        string source = "bunch of text";
        string regex = "<div id=\"Specs\" class=[\"']([^\"']*)[\"']>";
        string regexReplaceTo = "<div id=\"Specs\" class=\"\">";
        string output = Regex.Replace(source, regex, regexReplaceTo);

The funny thing is that it is working! :\ I was using incorrect source string to do it! Dunno! Thanks everyone for your help! — Andrew
– Andrew, Commented Mar 20, 2012 at 14:25

Dr.Kameleon · Accepted Answer · 2012-03-20 02:08:16Z

4

What about...

Regex to match : class=\"[A-Za-z0-9_\-]+\"
Replace with : class=\"\"

This way, we ignore the first part (id="Specs", etc) and just replace the class name... with nothing.

answered Mar 20, 2012 at 2:08

Dr.Kameleon

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2 Comments

Robbie Over a year ago

But what if he only wants to clear the class attributes of #specs divs? Which I (i could be wrong) presume he does?

Dr.Kameleon Over a year ago

well, if that is the case, you could add the frontmost part as well, I suppose... like : \id=\"Specs\" class=\"[A-Za-z0-9_\-]+\"

Erik Philips · Accepted Answer · 2012-03-20 02:54:32Z

Looks like another case of http://www.codinghorror.com/blog/2008/06/regular-expressions-now-you-have-two-problems.html. What happens to the following valid tags with a Regex?

<div class="reversed" id="Specs">            
<div  id="Specs"  class="additionalSpaces" >     
<div id="Specs" class="additionalAttributes" style="" >

I don't see a how using Linq2Xml wouldn't work with any combination:

XElement root = XElement.Parse(xml); // XDocument.Load(xmlFile).Root 
var specsDivs = root.Descendants()
                    .Where(e => e.Name == "div"
                           && e.Attributes.Any(a => a.Name == "id")
                           && e.Attributes.First(a => a.Name == "id").Value == "Specs"
                           && e.Attributes.Any(a => a.Name == "class"));
foreach(var div in specsDivs)
{
  div.Attributes.First(a => a.Name == "class").value = string.Empty;
}
string newXml = root.ToString()

jessehouwing · Accepted Answer · 2012-03-20 11:05:39Z

If your input isn't XML compliant, which most HTML isn't, then you can use the HTML Agility Pack to parse the HTML and manipulate the contents. With the HTML Agility PAck, combined with Linq or Xpath, the order of your attributes no longer matters (which it does when you use Regex) and the overall stability of your solution increases a lot.

Using the HTML Agility Pack (project page, nuget), this does the trick:

HtmlDocument doc = new HtmlDocument();
doc.LoadHtml("your html here"); 
// or doc.Load(stream);

var nodes = doc.DocumentNode.DescendantNodes("div").Where(div => div.Id == "Specs");

foreach (var node in nodes)
{
    var classAttribute = node.Attributes["class"];
    if (classAttribute != null)
    {
        classAttribute.Value = string.Empty;
    }
}

var fixedText = doc.DocumentNode.OuterHtml;
//doc.Save(/* stream */);

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