PHP自动生成月历代码

<?php
function calendar($MM,$YYYY)
{
if($MM=="") $MM = date("m");
if($YYYY=="") $YYYY = date("Y");
if(checkdate($MM,1,$YYYY)){
$stringDate = strftime("%d %b %Y",mktime (0,0,0,$MM,1,$YYYY));
$days = strftime("%d",mktime (0,0,0,$MM+1,0,$YYYY));
$firstDay = strftime("%w",mktime (0,0,0,$MM,1,$YYYY));
$lastDay = strftime("%w",mktime (0,0,0,$MM,$days,$YYYY));
$printDays = $days;
$preMonth = strftime("%m",mktime (0,0,0,$MM-1,1,$YYYY));
$preYear = strftime("%Y",mktime (0,0,0,$MM-1,1,$YYYY));
$nextMonth = strftime("%m",mktime (0,0,0,$MM+1,1,$YYYY));
$nextYear = strftime("%Y",mktime (0,0,0,$MM+1,1,$YYYY));
print("<table border=\"1\" cellpadding=\"1\" cellspacing=\"1\">");
print("<tr><th valign=\"top\"><a href=\"".$_SERVER['PHP_SELF']."?NB=".$_GET["NB"]."&MM=".$preMonth."&YY=".$preYear."\">P</a></th>");
print("<th colspan=\"5\" valign=\"top\">".strftime("%b %Y",mktime (0,0,0,$MM,1,$YYYY))."</th>");
print("<th valign=\"top\"><a href=\"".$_SERVER['PHP_SELF']."?NB=".$_GET["NB"]."&MM=".$nextMonth."&YY=".$nextYear."\">N</a></th></tr>");
print("<tr style=\"font-family: Verdana; font-size:x-small\">");
print("<th>Sun</th><th>Mon</th><th>Tue</th><th>Wed</th><th>Thu</th><th>Fri</th><th>Sat</th></tr>");
$currentDays = 1;
for($a=1;$a<=5;$a++){
print("<tr align=\"left\" valign=\"top\" style=\"font-family: Verdana; font-size:x-small\">");
$diffDays = $firstDay-$lastDay;
if($firstDay>$lastDay && $currentDays ==1 && ($diffDays<>1)){
for($x=$lastDay;$x>=0;$x--){
$printDays = $days-$x;
print("<td>$printDays</td>");
}
for($z=1;$z<$firstDay-$lastDay;$z++){
print("<td>&nbsp;</td>");
}
for($y=$firstDay;$y<7;$y++){
print("<td>$currentDays</td>");
$currentDays++;
}
}
elseif($firstDay!=0 && $currentDays==1){
for($z=1;$z<=$firstDay;$z++){
print("<td>&nbsp;</td>");
}
for($y=$firstDay;$y<7;$y++){
print("<td>$currentDays</td>");
$currentDays++;
}
}
else {
for($u=1;$u<=7 && $currentDays<=$days;$u++){
print("<td>$currentDays</td>");
$currentDays++;
}
}
print("</tr>");
}
print("</table>");
}
}

echo calendar(09,2008);
?>