php 日历

//$year=2009;
//$month=2;
//$day=15;
$month=$_GET['month'];
$year=$_GET['year'];
$day=$_GET['day'];
if($month=='')
  $month=date('m');
if($day=='')
  $day=date('d');
if($year=='')
  $year=date('Y');

 function prt_calendar($month,$day,$year){
   $nextMonth=$month+1;
   $nextYear=changeYear($year,$nextMonth);
   $preMonth=$month-1;
   $preYear=changeYear($year,$preMonth);
   $firstDay=date("w",mktime(0,0,0,$month,1,$year));
   $countMonth=date("t",mktime(0,0,0,$month,1,$year));
   echo "<table border='1' alagin='center' bgcolor='bisque' width='50%'><tr><td colspan='7'"
       ." align='center'><a href='calendar.phtml?year=$preYear&month=$preMonth'>"
       ."上月</a>&nbsp;$year-$month-$day&nbsp;"
       ."<a href='calendar.phtml?year=$nextYear&month=$nextMonth'>下月</a></td></tr>";
   echo "<tr align='center'><td><font color='red'>日</td><td>一</td><td>二</td><td>三</td>"
       ."<td>四</td><td>五</td><td>六</td></tr>";
   echo "<tr align='center'>";
   if($firstDay)
     echo "<td colspan='$firstDay'>&nbsp;</td>";
   for($i=$firstDay+1;$i<($countMonth+$firstDay+1);$i++){
     $bgcolor=day_color($month,$day,$year,($i-$firstDay));
     $color=font_color($month,($i-$firstDay),$year);
     echo "<td '$bgcolor'><font color='$color'>".($i-$firstDay)."</font></td>";
     if($i%7==0)
       echo "</tr><tr align='center'>";
   }
   $col=8-$i%7;
   if($col!=7)
     echo "<td colspan='$col'>&nbsp;</td></tr>";
   else
     echo "</tr></table>";
 }
function font_color($month,$day,$year){
   $sunday=date("w",mktime(0,0,0,$month,$day,$year));
   if($sunday=="0"||$sunday=="6"){
      return "red";
   }else{
      return "grey";
   }
}
function day_color($month,$day,$year,$today){
  $show_today=date("d",mktime(0,0,0,$month,$day,$year));
  $sys_today=date("d",mktime(0,0,0,$month,$today,$year));
  if($show_today==$sys_today){
     return "bgcolor='darkgray'";
  }else{
     return "";
  }
}
function changeYear($year,&$month){
  if($month<=0){
     $month=12;
     return $year-1;
  }
  if($month>12){
     $month=1;
     return $year+1;
  }
  return $year;
}