<?
$week = array('日','月','火','水','木','金','土');

#曜日を得る
function get_youbi($ymd,$i)
{
  global $week;
  $youbi = date("w", strtotime($ymd));
  if($i == 0){
    return $youbi;
  } else {
    return $week[$youbi];
  }
}

#月の最後の曜日を得る
function get_last_day($ymd)
{
  $year = date("Y", strtotime($ymd)); 
  $month = date("m", strtotime($ymd)); 
  $nissu = get_nissu($ymd); 
  return date("w", strtotime("$year/$month/$nissu"));
}

#月の日数を得る
function get_nissu($ymd)
{
  return date("t", strtotime($ymd));
}

#月の週数を得る
function get_weeks($ymd)
{
  $year = date("Y", strtotime($ymd)); 
  $month = date("m", strtotime($ymd)); 
  $nissu = get_nissu($ymd); 
  $b_youbi = date("w", strtotime("$year/$month/1"));
  $l_youbi = date("w", strtotime("$year/$month/$nissu"));
  return ($b_youbi+$nissu+(6-$l_youbi))/7;
}

#指定した年月日より+/-Ｎ日のymd(current ymd, +/-days) --> new ymd;
function get_pm_ymd($ymd,$day)
{
  $getday = date("Y/n/j",strtotime("$day day $ymd"));
  return $getday;
}
?>