Here I have described how to read and write data in XML file using C#.

For reading and writing data in XML file we used here DataTable. With the help of DataTable we insert new record, updating and searching XML file’s data.

DataTable dt = new DataTable("info");  
 
dt.ReadXmlSchema(Server.MapPath("XMLFile.xml"));
                dt.ReadXml(Server.MapPath("XMLFile.xml"));

Insert Data into XML File

Case 1:- If no XML file has in project then first insert data in DataTable then ‘WriteXml’ properties created a XML file in project and insert data.

DataTable dt = new DataTable("info");
 
//adding up 6 columns to datatable
dt.Columns.Add("id", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Age", typeof(int));
dt.Columns.Add("Salary", typeof(double));
dt.Columns.Add("Country", typeof(string));
dt.Columns.Add("City", typeof(string));
 
//add a row in DataTable and insert data from TextBox
dt.Rows.Add(txtId.Text.Trim(), txtName.Text.Trim(), txtAge.Text.Trim(), txtSalary.Text.Trim(), txtCountry.Text.Trim(), txtCity.Text.Trim());
dt.AcceptChanges();
 
//Write DataTable Data into XML file(XML file are created in project before writing data)
dt.WriteXml(Server.MapPath("XMLFile.xml"));

 Case 2:-If XML File exist then DataTable read Schema of existing XML file and then insert data into XML file with the help of DataTable

DataTable dt = new DataTable("info");  
 
if (File.Exists(Server.MapPath("XMLFile.xml")))
 {
    dt.ReadXmlSchema(Server.MapPath("XMLFile.xml"));
    dt.ReadXml(Server.MapPath("XMLFile.xml"));
    dt.Rows.Add(txtId.Text.Trim(), txtName.Text.Trim(), txtAge.Text.Trim(),               txtSalary.Text.Trim(), txtCountry.Text.Trim(), txtCity.Text.Trim());
    dt.AcceptChanges();
    dt.WriteXml(Server.MapPath("XMLFile.xml"));
 }

Searching Data in XML file

DataTable dt = new DataTable("info");  
 
if (txtId.Text != null)
      {
        dt.ReadXmlSchema(Server.MapPath("XMLFile.xml"));
        dt.ReadXml(Server.MapPath("XMLFile.xml"));
        DataRow[] data = dt.Select("Id='" + txtId.Text + "'");
         if (data.Length != 0)
          {
           txtName.Text= data[0][1].ToString();
           txtAge.Text= data[0][2].ToString();
           txtSalary.Text= data[0][3].ToString();
           txtCountry.Text= data[0][4].ToString();
           txtCity.Text= data[0][5].ToString();
                    btnUpdate.Enabled= true;
            btnInsert.Enabled= false;
                }
                else
                {
                    txtName.Text= txtAge.Text = txtSalary.Text = txtCountry.Text = txtCity.Text = "";
                    txtName.Focus();
                    btnUpdate.Enabled= false;
                    btnInsert.Enabled= true;
                }
            }

Updating Data in XML file

DataTable dt = new DataTable("info");  
 
dt.ReadXmlSchema(Server.MapPath("XMLFile.xml"));
            dt.ReadXml(Server.MapPath("XMLFile.xml"));
            DataRow[] data = dt.Select("Id='" + txtId.Text + "'");
            data[0][1]= txtName.Text.Trim();
            data[0][2]= txtAge.Text.Trim();
            data[0][3]= txtSalary.Text.Trim();
            data[0][4]= txtCountry.Text.Trim();
            data[0][5]= txtCity.Text.Trim();
            dt.AcceptChanges();
            dt.WriteXml(Server.MapPath("XMLFile.xml"));