How to get the number of days in a given month in Ruby, accounting for year?

Question

I\'m sure there\'s a good simple elegant one-liner in Ruby to give you the number of days in a given month, accounting for year, such as \"February 1997\". What is it?

Answer 1

This is the implementation from ActiveSupport (a little adapted):

COMMON_YEAR_DAYS_IN_MONTH = [nil, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

def days_in_month(month, year = Time.now.year)
   return 29 if month == 2 && Date.gregorian_leap?(year)
   COMMON_YEAR_DAYS_IN_MONTH[month]
end