isenk aja mas

 <select name="ttl" required>

<?php
$tglLahir = 05; // misalkan tgl nya 05
for($tgl=1; $tgl<=31; $tgl++){
/*
if($tgl<=9) { echo "<option value='0$tgl'>0$tgl</option>"; }
else { echo "<option value='$tgl'>$tgl</option>"; }

echo "<option selected='selected' value='$tglLahir'>$tglLahir</option>";
*/
$tmp= "<option %s value='%s'>%02s</option>";
$selected= (int)$tglLahir==$tgl?'selected':'';
$val=$title=$tgl;
    printf($tmp, $selected, $val, $title);
}

?>

</select>