I create excel file using php.It has contain Query Result data from database.Excel file generate and download very well but when i opened i found it gives some format error and some coding error also.

function generate_excel($conn) {
$filename = "website_data_" . date('Ymd') . ".xls";
function cleanData(&$str) {
$str = preg_replace("/\t/", "\\t", $str);
$str = preg_replace("/\r?\n/", "\\n", $str);
if (strstr($str, '"'))
$str = '"' . str_replace('"', '""', $str) . '"';
}
header("Content-Disposition: attachment; filename=\"$filename\"");
header("Content-type: application/octet-stream;charset=utf-8");
$flag = false;
$qry = "SELECT ContactId,UniqueContactId FROM Contacts ORDER BY ContactId ";
$stmt = sqlsrv_query($conn, $qry);
$row = sqlsrv_fetch_array($stmt, SQLSRV_FETCH_ASSOC);
while (false !== ($row = sqlsrv_fetch_array($stmt, SQLSRV_FETCH_ASSOC))) {
if (!$flag) {
// display field/column names as first row
echo implode("\t", array_keys($row)) . "\r\n";
$flag = true;
}
array_walk($row, 'cleanData');
echo implode("\t", array_values($row)) . "\r\n";
}
exit;
}