title: export datatable to CSV with Save File Dialog box - C#
body: <p>Struggling to get my CSV export to display the Save File dialog box up.  It saves to file ok, but doesn't let the user save.  Can anybody see where I might be going wrong with the code please?</p>
  
  <pre><code>string filename = Server.MapPath("~/download.csv");
  StreamWriter sw = new StreamWriter(filename, false);
  
  int iColCount = dt.Columns.Count;
  for (int i = 0; i &lt; iColCount; i++)
  {
      sw.Write(dt.Columns[i]);
      if (i &lt; iColCount - 1)
      {                
          sw.Write(",");
      }
  }
  sw.Write(sw.NewLine);
  
  foreach (DataRow dr in dt.Rows)
  {
      for (int i = 0; i &lt; iColCount; i++)
      {
          if (!Convert.IsDBNull(dr[i]))
          {
              sw.Write(dr[i].ToString());
          }
          if (i &lt; iColCount - 1)
          {
              sw.Write(",");
          }
      }
      sw.Write(sw.NewLine);
  }
  sw.Close();
  
  Response.Clear();
  Response.ContentType = "application/csv";
  Response.AddHeader("Content-Disposition", "attachment; filename=download.csv");
  Response.WriteFile(filename);
  Response.Flush();
  Response.End();
  </code></pre>
  
  <p>I thought the Content Disposition line that brought up the dialog box, but maybe there is something else I need to do.</p>
  
  <p>Thanks</p>