gvFile error while compling code to save output in Excel format

I am using the following code to write output of datagrid into an excel file.

I am getting error message
"The name gvFiles cannot be use din the context"

System.IO.StringWriter sw = new System.IO.StringWriter();
System.Web.UI.HtmlTextWriter htw = new System.Web.UI.HtmlTextWriter(sw);
// Render grid view control.
gvFiles.RenderControl(htw);
// Write the rendered content to a file.
string renderedGridView = sw.ToString();
File.WriteAllText(@"C:\temp\ExportedFile.xlsx", renderedGridView);

I can see the output in the datagrid?
How do I save to Excel file in C#?

Tags: C#