php生成年月日下载列表的方法

function mdy($mid = "month",$did = "day",$yid = "year",$mval,$dval,$yval)
{
? if(empty($mval)) $mval = date("m");
? if(empty($dval)) $dval = date("d");
? if(empty($yval)) $yval = date("Y");
? $months = array(1 => "January",2 => "February",3 => "March",4 => "April",5 => "May",6 => "June",7 => "July",8 => "August",9 => "September",10 => "October",11 => "November",12 => "December");
? $out = "<select name='$mid' id='$mid'>";
? foreach($months as $val => $text)
??? if($val == $mval) $out .= "<option value='$val' selected>$text</option>";
??? else $out .= "<option value='$val'>$text</option>";
? $out .= "</select> ";
? $out .= "<select name='$did' id='$did'>";
? for($i = 1; $i <= 31; $i++)
??? if($i == $dval) $out .= "<option value='$i' selected>$i</option>";
??? else $out .= "<option value='$i'>$i</option>";
? $out .= "</select> ";
? $out .= "<select name='$yid' id='$yid'>";
? for($i = date("Y"); $i <= date("Y") + 2; $i++)
??? if($i == $yval) $out.= "<option value='$i' selected>$i</option>";
??? else $out.= "<option value='$i'>$i</option>";
? $out .= "</select>";
? return $out;
}