21.1 a) enumerator (or
foreach statement). b)
ArrayList. c) indexer. d)
21.2 a) True. b) True. c) False. The class must also implement property
Current. d) False. An
ArrayList stores only
objects. Autoboxing occurs when adding a value type to the
ArrayList. You can prevent boxing by instead using generic class
List with a value type. e) True. f) False. A
Hashtable cannot contain duplicate keys. g) True. h) False.
Dictionary is a class;
IDictionary is an interface. i) False. An enumerator cannot be used to change the values of elements. j) False. With hashing, as the load factor increases, there are fewer available slots relative to the total number of slots, so the chance ...