When to use a HashTable

Question

In C#, I find myself using a List, IList or IEnumerable 99% of the time. Is there a case when it would be b

Answer 1

There's no way of telling exactly without knowing what the collection is for, but unless the items in your collection are unique you cannot use a hashtable, as there will be nothing to use as a key. So perhaps the rule of thumb you are looking for is that if your members are all different and you want to pull individual instances out by key, use a hashtable. If you have a bunch of items that you wish to treat in the same way (such as doing a foreach on the entire set) use a list.