Export Datatable to Excel in C#

public void ExportExcel(DataTable dt, string fileName)
{


// string attachment = "attachment; filename=city.xls";
Response.ClearContent();
Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.xls", fileName));
Response.ContentType = "application/vnd.ms-excel";
string tab = "";
foreach (DataColumn dc in dt.Columns)
{
Response.Write(tab + dc.ColumnName);
tab = "\t";
}
Response.Write("\n");
int i;
ClearViewstate();
foreach (DataRow dr in dt.Rows)
{
tab = "";
for (i = 0; i < dt.Columns.Count; i++)
{
Response.Write(tab + dr[i].ToString());
tab = "\t";
}
Response.Write("\n");
}
Response.End();
ClearViewstate();


}