How to Export Gridview Data to Excel Format using Asp.net

In this post i am going to Explain how to How to Convert Gridview data to Excel Format .
 In Source Code  we need to write EnableEventValidation="false" for Verify Rendering In Server Form

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" EnableEventValidation="false" %>
first we need to Bind Gridview after that we need to write this code in button click event.

protected void btnExcel_Click(object sender, EventArgs e)
    {
        Response.ClearContent();
        Response.Buffer = true;
        Response.AddHeader("content-disposition", string.Format("attachment; filename={0}", "EmployeeDetals.xls"));
        Response.ContentType = "application/ms-excel";
        StringWriter sw = new StringWriter();
        HtmlTextWriter htw = new HtmlTextWriter(sw);
        GridView1.AllowPaging = false;
        //Change the Header Row back to white color
        GridView1.HeaderRow.Style.Add("background-color", "#FFFFFF");
        //Applying stlye to gridview header cells
        for (int i = 0; i < GridView1.HeaderRow.Cells.Count; i++)
        {
            GridView1.HeaderRow.Cells[i].Style.Add("background-color", "#507CD1");
        }
        int j = 1;
        //This loop is used to apply stlye to cells based on particular row
        foreach (GridViewRow gvrow in GridView1.Rows)
        {
            gvrow.BackColor = Color.White;
            if (j <= GridView1.Rows.Count)
            {
                if (j % 2 != 0)
                {
                    for (int k = 0; k < gvrow.Cells.Count; k++)
                    {
                        gvrow.Cells[k].Style.Add("background-color", "#EFF3FB");
                    }
                }
            }
            j++;
        }
        GridView1.RenderControl(htw);
        Response.Write(sw.ToString());
        Response.End();
    }