c# - remove html node from htmldocument :HTMLAgilityPack

Question

In my code, I want to remove the img tag which doesn't have src value. I am using HTMLAgilitypack's HtmlDocument object. I am finding the img which doesn't have src value and trying to remove it.. but it gives me error Collection was modified; enumeration operation may not execute. Can anyone help me for this? The code which I have used is:

foreach (HtmlNode node in doc.DocumentNode.DescendantNodes())
{
    if (node.Name.ToLower() == "img")
    {                            
           string src = node.Attributes["src"].Value;
           if (string.IsNullOrEmpty(src))
           {
               node.ParentNode.RemoveChild(node, false);    
           }
   }
   else
   {
             ..........// i am performing other operations on document
   }
}

Answer 1

It seems you're modifying the collection during the enumeration by using HtmlNode.RemoveChild method.

To fix this you need is to copy your nodes to a separate list/array by calling e.g. Enumerable.ToList<T>() or Enumerable.ToArray<T>().

var nodesToRemove = doc.DocumentNode
    .SelectNodes("//img[not(string-length(normalize-space(@src)))]")
    .ToList();

foreach (var node in nodesToRemove)
    node.Remove();

If I'm right, the problem will disappear.