Find the class, type, mode and storage mode of the following values:

• Inf
• NA
• NaN
• ""

That means creating sixteen objects:

• Store the classes in objects with the prefix class_ (e.g. class_Inf, class_NA etc.)
• Store the types in objects with prefix type_ (e.g. type_NA, type_NaN etc.)
• Store the modes in objects with prefix mode_ (e.g. mode_Inf, mode_NaN etc.)
• Store the storage modes in objects with the prefix storage_ (e.g. storage_NA, storage_empty etc.)

The objects for the empty string "" can have the suffix _empty (e.g. class_empty, type_empty etc.). Beware of small and capital letters!

(from: Cotton, 2013, Learning R, O’Reilly)