title: write datagridview data in to xml file
body: <p>I am new to c#, this may be very easy question.</p>
  
  <p>In my application there is a <code>Form</code> in which I have datagridview <code>dgvBill</code> and a Button <code>btnClick</code>. I declared columns to it by clicking the extender and selecting <code>add columns</code>. After executing the form, I written some text to each column in <code>dgvBill</code>. When I click on <code>btnClick</code> it is creating an xml file but with no data in it. (why the data is not being added ?)</p>
  
  <p>The created XML file looks like this:</p>
  
  <pre><code>&lt;?xml version="1.0" standalone="yes"?&gt;
  &lt;NewDataSet /&gt;
  </code></pre>
  
  <p>I have tried the below code:</p>
  
  <p><strong>btnClick Event</strong></p>
  
  <pre><code>DataSet ds = new DataSet();
  ds.WriteXml(@"..\..\Customer_Info\" + lblCustId.Text + ".xml");
  dgvBill.DataSource = ds;  /* also tried ds.Tables[0] */
  </code></pre>
  
  <p><code>lblCustId</code> is a label in the <code>Form</code></p>
  
  <p><em>Optional</em>: can I make each cell of datagridview into ComboBox?</p>
  
  <p>Thanks in advance.</p>