# last day of month

## Perl

### array

    $ perl -e '@d=qw(31 28 31 30 31 30 31 31 30 31 30 31);
      ($y,$m)=@ARGV;
      warn $m--==2?$d[$m]+($y%4==0)-($y%100==0)+($y%400==0):$d[$m]' 2010 2
    28 at -e line 1.

### Time::Piece

    $ perl -MTime::Piece -e '
      warn Time::Piece->strptime(join(" ",@ARGV),"%Y %m")->month_last_day' 2010 2
    28 at -e line 1.

### DateTime

    $ perl -MDateTime -e '
      warn DateTime->last_day_of_month(year=>shift,month=>shift)->day;' 2010 2
    28 at -e line 1.

### Date::Calc

    $ perl -MDate::Calc -e '
      warn Date::Calc::Days_in_Month(@ARGV)' 2010 2
    28 at -e line 1.

sfujiwara++

## memo

### leap year

* 2010 2 -> 28
  * 2010 2 -> 29 (PS3)
* 2012 2 -> 29
* 2100 2 -> 28
* 2400 2 -> 29