['dir1', 'dir2', 'file'].to_param => "dir1/dir2/file"
['test', 'file1', 'file2'].to_sentence(:connector => 'and') => "test, file1, and file2"options
様々の便利な文字列表現や
その他のオブジェクトから "日付" を得ます。
"2005/12/24 11:00:00".to_date.to_s => "2005-12-24"
Time.now.next_month.to_date.to_s => "2006-07-04"
Time.now.to_formatted_s(:short) => "04 Jun 19:56" Time.now.to_formatted_s(:long) => "June 04, 2006 19:56"
1.even? # => false 1.odd? # => true 2.even? # => true 2.odd? # => false
10.multiple_of?(2) # => true
1.ordinalize # => "1st" 3.ordinalize # => "3rd" 10.ordinalize # => "10th"
1.gigabyte # => 1073741824