PHP生成月历代码

<?php
/*  
Function Written by Nelson Neoh @3/2004.  
For those who wants to utilize this code, please do not remove this remark.  
If you have done any enhancement to this code, please post the copy at http://www.dev-club.com PHP board.  Thank you.
Function usage: calendar(Month,Year)
*/
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> </td>");
                }
                for($y=$firstDay;$y<7;$y++){
                    print("<td>$currentDays</td>");
                    $currentDays++;
                }
            } elseif($firstDay!=0 && $currentDays==1){
                for($z=1;$z<=$firstDay;$z++){
                    print("<td> </td>");
                }
                for($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>");
    }
}
?>