How to Export Encoded Data into CSV Files using asp.net c#

//Data Tabel

//HTML

<asp:Button ID="btnExport" runat="server" Text="Button" OnClick="btnExport_Click" />

//Code Behind

protected void btnExport_Click(object sender, EventArgs e)

    {

        DataTable dt = GetData();

        StringBuilder builder = new StringBuilder();

        var count = 0;

        // write header in String Builder

        foreach (DataColumn column in dt.Columns)

        {

            count++;

            string content = column.ColumnName + "";

            content = content.Replace("\"", "\"\"");

            builder.Append(string.Format("{0}{1}{0}", Convert.ToChar(34), content));

            if (count < dt.Columns.Count)

                builder.Append(",");

        }

        builder.Append(Environment.NewLine);

        //Write content in String Builder

        foreach (DataRow row in dt.Rows)

        {

            for (int i = 0; i < row.ItemArray.Length; i++)

            {

                if (!Convert.IsDBNull(row[i]))

                {

                    string content = row[i].ToString() + "";

                    content = content.Replace("\"", "\"\"");

                    builder.Append(string.Format("{0}{1}{0}", Convert.ToChar(34), content));

                    if (i < row.ItemArray.Length - 1)

                        builder.Append(",");

                }

            }

            builder.Append(Environment.NewLine);

        }

        // get file and write inside file

        using (var streamWriter = new StreamWriter(@"C://Users//Vipin Gehlot//Desktop//yy.csv", false, Encoding.UTF8))

        {

            streamWriter.Write(builder.ToString());

            streamWriter.Flush();

            streamWriter.Close();

        }

    }

}

//Result