php实现的日历程序

<?php
////判断$year和$month是否为空,如果为空就获取系统当前日期,否则用$_get获取
$year = empty($_get['year']) ? date("y"): $_get["year"];
$month = empty($_get['month']) ? date("m"): $_get["month"];
////获取当前日期////
$today = date("ymj");
////初始化日期数组////
$maxday = array("1","2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20",
"21","22","23","24","25","26","27","28","29","30","31");
$maxday_count = count($maxday);
////初始化星期数组////
$weekday = array("<font color='red'>sun</font>","mon","tue","wed","thu","fri","<font color='red'>sat</font>");
$weekday_count = count($weekday);
$daynum = 0;
$space = "<td> </td>";
$col = 0;
////打印表格头部////
?>
<form action="calendar.php" method="post" name="linked">
<table><tr><td colspan=3 align=center><a href="?year=<?php if($year-1 > 1900)echo $year-1;else echo $year;?>&month=<?php echo $month?>" onclick="javascript:document.linked.submit();" name="year"><<</a> <?php echo $year?> <a href="?year=<?php if($year+1 <2999) echo $year+1;else echo $year;?>&month=<?php echo $month?>" onclick="javascript:document.linked.submit();" name="year">>></a></td>
<td> </td><td colspan=3 align=center><a href="?year=<?php echo $year?>&month=<?php if($month-1 >0) if($month-1 < 10)echo "0".($month-1); else echo $month-1; else echo $month;?>" onclick="javascript:document.linked.submit();" name="month"><<</a> <?php echo $month;?> <a href="?year=<?php echo $year?>&month=<?php if($month+1 <13) if($month+1 <10) echo "0".($month+1);else echo ($month+1); else echo $month;?>" onclick="javascript:document.linked.submit();" name="month">>></a></td></tr><tr><td colspan="8"></td></tr><tr>
<?php
////打印星期列表////
while(list(,$weekvalue) = each($weekday))
 echo "<td align=center> ".$weekvalue." </td>";
echo "</tr>";
////打印日期列表////
//当月份为4,6,9,11的时候,从数组末尾删除一个值,也就是删除31这个值.
if($month == 4 or $month == 6 or $month == 9 or $month == 11)
{
 array_pop($maxday);
 $maxday_count--;
}
//先判断月份是否为2月,如果是的话再判断年份是否为闰年,如果是的话就从数组尾部移除2个值,否则就移除3个值.
if($month == 2)
{
 if($year % 4 == 0)
 {
 array_pop($maxday);
 array_pop($maxday);
 $maxday_count-=2;
 }
 else
 {
 array_pop($maxday);
 array_pop($maxday);
 array_pop($maxday);
 $maxday_count-=3;
 }
}
////打印日期////
while($daynum < $maxday_count)
{
echo "<tr>";
 while(list($colnum,$dayvalue) = each($maxday))
 {
  //判断当前日期为一星期中的哪一天
  $dayweek = date("w",strtotime($year."-".$month."-".$dayvalue));
  //当当前日期处于第1个,也就是每个月的第1天的时候,在它前面补上相应的空格子
  if($dayvalue == 1)
   for($i=0;$i<$dayweek;$i++)
   echo $space;//打印每个月空出的几个格子
  $daynum++;
  //当打印日期的时候与当前日期字符串进行比较,如果相等就将字体标为红色.
  if($year.$month.$dayvalue == $today)
  {
   $u1 = "<b><u>";
   $u2 = "</b></u>";
  }
  else
  {
   $u1 = "";
   $u2 = "";
  }
  if($dayweek == 0 or $dayweek == 6)
   $color = "red";
  else
   $color = "black";
  echo "<td align=center><font color=".$color."> ".$u1.$dayvalue.$u2." </font></td>";
  //用本周第几天这个值加1,如果是7的倍数就换行退出此轮循环(换行打印)
  if(($dayweek+1) % 7 == 0)
  {
   $col++;
   break;
  }
 }
echo "</tr>";
}
?>