Question

Normally when I need to have a list of ints/strings/etc. I create a list like:

var list = new List<string>

And then I create a hashtable that contains all the strings, and I don’t insert into the list unless it isn’t in the hashtable i.e. to enforce unique items in the list.

Is there a datatype that can satisfy both of these requirements for me?

Answer 1

There is. Use HashSet:

var set = new HashSet<int>();
set.Add(4);
set.Add(4);   // there is already such an element in the set, no new elements added

Keep in mind, though, that it does not guarantee you the order of elements.