php日期所在月的天数

php日期所在月的天数

 public function daysOfMonth ($year=NULL,$month=NULL) {
  if ($year===NULL) {
   $year = $this->getPart('yy');
  }
  if ($month===NULL) {
   $month = $this->getPart('mm');
  }
  if ($month==2)
  {
   if (($year % 4 == 0 && $year % 100 != 0) || $year %

400 == 0)
    $result = 29;
   else
    $result = 28;
  }
  elseif ($month == 4 || $month == 6 || $month == 9 || $month

== 11)
   $result = 30;
  else
   $result = 31;
  return $result;
 }