//获取今日开始时间戳和结束时间戳 
 $beginToday=mktime(0,0,0,date('m'),date('d'),date('Y')); 
 $endToday=mktime(0,0,0,date('m'),date('d')+1,date('Y'))-1; 
 //获取昨日起始时间戳和结束时间戳 
 $beginYesterday=mktime(0,0,0,date('m'),date('d')-1,date('Y')); 
 $endYesterday=mktime(0,0,0,date('m'),date('d'),date('Y'))-1; 
 //获取本周起始时间戳和结束时间戳  
 $beginThisweek = mktime(0,0,0,date('m'),date('d')-date('w')+1,date('y')); 
 $endThisweek=time(); 
 //获取上周起始时间戳和结束时间戳 
 $beginLastweek=mktime(0,0,0,date('m'),date('d')-date('w')+1-7,date('Y')); 
 $endLastweek=mktime(23,59,59,date('m'),date('d')-date('w')+7-7,date('Y')); 
 //获取本月起始时间戳和结束时间戳 
 $beginThismonth=mktime(0,0,0,date('m'),1,date('Y')); 
 $endThismonth=mktime(23,59,59,date('m'),date('t'),date('Y')); 
 //上个月的起始时间: 
 $begin_time = strtotime(date('Y-m-01 00:00:00',strtotime('-1 month'))); 
 $end_time = strtotime(date("Y-m-d 23:59:59", strtotime(-date('d').'day'))); 
 $begin_year = strtotime(date("Y",time())."-1"."-1"); //本年开始 
 $end_year = strtotime(date("Y",time())."-12"."-31"); //本年结束 
 //现在的时间到第二天凌晨相差的时间戳 
 $time = (strtotime(date('Y-m-d'))+3600*24) - time() ;

//上周起始时间
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),date("d")-date("w")+1-7,date("Y")));
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d")-date("w")+7-7,date("Y")));
//本周起始时间
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),date("d")-date("w")+1,date("Y")));
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d")-date("w")+7,date("Y")));
//上月起始时间
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m")-1,1,date("Y")));
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m") ,0,date("Y")));
//本月起始时间
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),1,date("Y")));
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("t"),date("Y")));
//本年起始时间
echo date(‘Y-01-01'); 
echo date(‘Y-12-31');

 $BeginDate=date('Y-m-01', strtotime(date("Y-m-d")));
  echo $BeginDate;
  echo "
";
  echo date('Y-m-d', strtotime("$BeginDate +1 month -1 day"));
  echo "
";

  echo " 本月共有:".date("t")."天";
  echo " 当前年份".date('Y');
  echo " 当前月份".date('m');
  echo " 当前几号".date('d');
  echo "
";

  $days = cal_days_in_month(CAL_GREGORIAN, 4, 2011);
  echo "返回2011-4的天数 ".$days."
";
  $days = date('t', strtotime("2011-4-1"));
  echo "返回2011-4的天数 ".$days."
";
  $days = date("t"); 
  echo "当前月的天数 ".$days."
";
 cal_days_in_month 的公用:返回某个历法中某年中某月的天数