Well, i needed something like that a few days ago and after Googling for couple of hours I ran across this this great library called HtmlAgilityPack.

Sure, you can do it by using C# WebBrowser control or MSHTML, but you will have to forget about performance or multithreading – it will eat all your memory and the CPU won’t know what’s hit it.

Now, back to the HtmlAgilityPack.
The usage is very simple, and the performance is great ( at least for my needs ).

Following is an example how we can find all images without an “alt” attribute, add it and resave the Html document.

            HtmlDocument HD = new HtmlDocument();
            HD.Load (@"e:\test.htm");
            var NoAltElements = HD.DocumentNode.SelectNodes("//img[not(@alt)]");
            if (NoAltElements != null)
            {
                foreach (HtmlNode HN in NoAltElements)
                {
                    HN.Attributes.Append("alt", "no alt image");
                }
            }

            HD.Save(@"e:\test.htm");

Will the following code compile and if yes what will be the result of it ?

static void Main(string[] args)
{
    int[] array = new[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    Func<int, int> func = i => {
                          Console.Write(array[i]);
                          return i;
                     };

    var result = array.Where(e => e <= func(2)).ToArray ();
}