//获取当前时间的时间戳
$time = time();
//获取某个时间点的时间戳
//2011-9-8 3:4:5
echo mktime(3,4,5,9,8,2011);
//设置默认时区
date_default_timezone_set("PRC");
//日期格式化
echo date("Y年m月d日 H:m:s");
//microtime — 返回当前 Unix 时间戳和微秒数
$ms = microtime();
//日历表
$year = 2017;
$month = 3;
$lastMonth = $month-1;
if($lastMonth ==0)$lastMonth = 12;
$firstday = mktime(16,23,0,$month,1,$year); //取所给年月的第一天的UNIX时间戳
$lastDays = mktime(16,23,0,$lastMonth,1,$year);
$days = date('t',$firstday); //返回指定月份的天数
echo"<div style='width: 300px'>";
   for($i = 1;$i<$days;$i++){
      echo"<p style='width: 20px;float: left;border: 1px solid red;margin: 5px 10px 5px 10px'>";
      echo$i;
      echo"</p>";
   }
echo"</div>";
echo"<hr style='clear: both'>";
$week = date("w",$firstday);
$days = date('t',$firstday); //返回指定月份的天数
$nowDay = date('t',$lastDays);
$day = mktime(16,23,0,3,23,2017);
echo$day;
echo"<hr>";
echo$firstday;
echo"<head><style>p{text-align: center;width: 40px;height: 30px;line-height: 30px;float: left;margin: 8px;border: 2px solid rebeccapurple}</style></head>";
echo"<div style='width: 420px'>";
for($j=1;$j<8;$j++){
   if($j==7){
      echo"<p>周日</p>";
   }else{
      echo"<p>周$j</p>";
   }
}
for($i = 1;$i<($days+$week);$i++){
   if($i<$week){
      echo"<p style='border: 2px solid lavender'>";
      echo$nowDay-(-$i)-$week+1;
      echo"</p>";
   }else{
      if($day == $firstday){
         echo"<p style='border: 2px solid green;'>";
         echo$i-$week+1;
         echo"</p>";
      }else{
         echo"<p style='border: 2px solid red;'>";
         echo$i-$week+1;
         echo"</p>";
      }
   }
}