how to export multiple Gridview into excel in asp.net

here,i got the solution ..

public override void VerifyRenderingInServerForm(Control control)
{
/* Verifies that the control is rendered */
}
protected void btnexport_Click(object sender, ImageClickEventArgs e)
{
try
{

Response.Clear();

Response.Buffer = true;



Response.AddHeader("content-disposition",

"attachment;filename=GridViewExport.xls");

Response.Charset = "";

Response.ContentType = "application/vnd.ms-excel";

StringWriter sw = new StringWriter();

HtmlTextWriter hw = new HtmlTextWriter(sw);


if (GridView2.Rows.Count!=0)
{
PrepareForExport(GridView2);
}
if (GridView4.Rows.Count!=0)
{
PrepareForExport(GridView4);

}

Table tb = new Table();

TableRow tr1 = new TableRow();

TableCell cell1 = new TableCell();

cell1.Controls.Add(GridView2);

tr1.Cells.Add(cell1);

TableCell cell3 = new TableCell();

cell3.Controls.Add(GridView4);

TableCell cell2 = new TableCell();

cell2.Text = " ";

//// if (rbPreference.SelectedValue == "2")
// // {

// tr1.Cells.Add(cell2);

// tr1.Cells.Add(cell3);

// tb.Rows.Add(tr1);

//// }

// //else
// //{

TableRow tr2 = new TableRow();

tr2.Cells.Add(cell2);

TableRow tr3 = new TableRow();

tr3.Cells.Add(cell3);

tb.Rows.Add(tr1);

tb.Rows.Add(tr2);

tb.Rows.Add(tr3);

//}

tb.RenderControl(hw);



//style to format numbers to string

string style = @" .textmode { mso-number-format:\@; } ";

Response.Write(style);

Response.Output.Write(sw.ToString());

Response.Flush();

}
catch (Exception ex)
{
Response.Write(ex.ToString());
}
finally
{
Response.End();

}




}


protected void PrepareForExport(GridView Gridview)
{

// Gridview.AllowPaging = Convert.ToBoolean(rbPaging.SelectedItem.Value);

GridView2.AllowPaging = false;
GridView4.AllowPaging = false;
btnview_Click1(this, null);
// Gridview.DataBind();



//Change the Header Row back to white color

Gridview.HeaderRow.Style.Add("background-color", "#FFFFFF");



//Apply style to Individual Cells

for (int k = 0; k < Gridview.HeaderRow.Cells.Count; k++)
{

Gridview.HeaderRow.Cells[k].Style.Add("background-color", "green");

}



for (int i = 0; i < Gridview.Rows.Count; i++)
{

GridViewRow row = Gridview.Rows[i];



//Change Color back to white

row.BackColor = System.Drawing.Color.White;



//Apply text style to each Row

row.Attributes.Add("class", "textmode");



//Apply style to Individual Cells of Alternating Row

if (i % 2 != 0)
{

for (int j = 0; j < Gridview.Rows[i].Cells.Count; j++)
{

row.Cells[j].Style.Add("background-color", "#C2D69B");

}

}

}

}