Should I use a Dictionary for collections with 10 items or less, or is there a better alternative?

Question

I have a list of objects and I need to find an object as quickly as possible (by it's name property). What data-structure should I use? I know I can use a Dictionary, but there wont ever be more than 10 items in the list, and if I remember correctly the dictionary is implemented as an array if the collection contains 10 items or less.

Thanks.

Answer 1

MSDN recommends the ListDictionary for collections with 10 items or less:

This is a simple implementation of IDictionary using a singly linked list. It is smaller and faster than a Hashtable if the number of elements is 10 or less. This should not be used if performance is important for large numbers of elements.

Answer 2

You may want to consider the System.Collections.Specialized.ListDictionary if you are certain there will be less than ten items.

Also consider the System.Collections.Specialized.HybridDictionary which switches behaviour (with a small overhead) should the size increase above a threshold, handy if your assumption is wrong.

Answer 3

Why not just use a Hashtable? It's in the System.Collections namespace.

Answer 4

Since you want fastest possible lookup by a property you should use Dictionary<Key, Value>. The size doesn't hurt you if you want fast lookup. It's not that a Dictionary<Key, Value> of just 10 items or less is taking up a ton of memory. Dictionary<Key, Value> has a constructor that takes an int to set the capacity.