Count specific XML Nodes within XML

Here's an example of counting all submenuid nodes in your xml document without loading it into memory:

var nodeCount = 0;
using (var reader = XmlReader.Create("test.xml"))
{
    while (reader.Read())
    {
        if (reader.NodeType == XmlNodeType.Element && 
            reader.Name == "submenuid")
        {
            nodeCount++;
        }
    }
}
Console.WriteLine(nodeCount);

Or if you prefer LINQ to XML:

var count = XDocument
    .Load("test.xml")
    .XPathSelectElements("//submenuid")
    .Count();

Use XmlDocument like this:

XmlDocument xmlD = new XmlDocument();
xmlD.Load(Server.MapPath("sample.xml"));
XmlNodeList xmlNL = xmlD.GetElementsByTagName("tagName");
xmlNL.Count;

You can use XPath function "count" as well. here is a example.

XPathDocument doc = new XPathDocument("c:\\test.xml");
int count = (int)doc.CreateNavigator().Evaluate("count(//submenuid)");

Below code is to find the count of a specific node in the XML Document

 private void browse_Click(object sender, EventArgs e)//file browse button
    {
        DialogResult result = openFileDialog1.ShowDialog();
        if (result == DialogResult.OK)
        {
            String file = openFileDialog1.FileName;
            if (Path.GetExtension(file) != ".xml")
            {
                MessageBox.Show("Please upload an vaild xml file");
                textBox1.Clear();
            }
            else
            {
                textBox1.Text = file;
            }
        }
    }  
 private void CountButton_Click(object sender, EventArgs e)//count button
    {
        int count = 0;
        string element = textBox2.Text;//Enter the node in the textbox
        XmlDocument readdoc = new XmlDocument();
            readdoc.Load(textBox1.Text);
            XmlElement root = readdoc.DocumentElement;
            XmlNodeList node = root.GetElementsByTagName(element);
            count = node.Count;
            MessageBox.Show(string.Format("Count of {0} node in the uploaded xml file is {1}", element, count.ToString()));
    }

If you have control of your xml

string xmlReturn="
<CMP>
<OMP3>
    <personmenu>
        <submenuid>502</submenuid>
        <submenuid>503</submenuid>
    </personmenu>
    <accountsmenu>
        <submenuid>517</submenuid>
        <submenuid>518</submenuid>
        <submenuid>519</submenuid>
    </accountsmenu>

    <reportsmenu>
        <submenuid>522</submenuid>
        <submenuid>528</submenuid>
        <submenuid>536</submenuid>
    </reportsmenu>
</OMP3>

<AMP3>
    <admissionmenu>
        <submenuid>702</submenuid>
        <submenuid>703</submenuid>
    </admissionmenu>
</AMP3>
</CMP>"
XmlDocument xmldoc = new XmlDocument();
xmldoc.LoadXml(xmlReturn);
XmlNodeList nodeListCount=xmldoc.GetElementsByTagName("submenuid");
int nodeCount = nodeListCount.Count;
Console.WriteLine(nodeCount);