C#

using System.Diagnostics;
using System.Net;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System;
using System.IO;
using System.Linq;

class Program
{
	static void Main()
	{
		StreamReader str = new StreamReader("C:\\Sample1.html");
		string strLings = str.ReadToEnd();
		int startIndex = strLings.IndexOf("<table>");
		int endInedx = strLings.IndexOf("</table>") + "</table>".Length - startIndex;
		string strTab = strLings.Substring(startIndex, endInedx);
		str.Close();
		StreamWriter strWr = new StreamWriter("C:\\test2.txt", true);
		strWr.Write(strTab);
		strWr.Close();
	}
}

<root>
  <element1 />
  <element2 attr1="text" attr2="text">
    <subelement21>
      <subsubelement attr1="text" attr2="text" />
      <subsubelement attr1="text" attr2="text" />
      ...
      <subsubelement attr1="text" attr2="text" />
    </subelement21>
  </element2>
</root>

XmlTextReader reader = new XmlTextReader("file.xml");
while(reader.Read()) {
  if (reader.NodeType == XmlNodeType.Element) {
    switch (reader.Name) {
      case "element1":
        break;
      case "element2":
        reader.MoveToAttribute("attr1");
        String att1 = reader.Value;
        reader.MoveToAttribute("attr2");
        String att2 = reader.Value;
        
        XmlReader subreader = reader.ReadSubTree();
        while(subreader.Read()) {
          if(subreader.NodeType == XmlNodeType.Element) {
            switch (reader.Name) {
              case "subsubelement":
                subreader.MoveToAttribute("attr1");
                String a1 = reader.Value;
                subreader.MoveToAttribute("attr2");
                String a2 = reader.Value;
                break;
          }
        }
        break;
    }
  }
}