c# SortedSet how to get an element out

问题

I am pretty new to this so forgive my noobishness here.

I am trying to edit an item in a c# sortedset if I find that the item exists. So I can use list.contains(value) and find that the value does exist in the list. But how do I get that item out of the list. Here is what I have. This gets really slow as my list size gets really big, so I'm guessing there must be a better way than this.

if (list.Contains(p))
{
     Person exists = list.First(person => person.Name.Equals(line[0]));
     // do something here to exists
}
else
{
    // just add the person to the list
}

回答1:

Do you really need SortedSet which is red-black tree? If you don't need sorting, you shouldn't use it. Have you considered HashSet or Dictionary instead which is more suitable (fast) for getting item by key?

In your case you probably need to create Dictionary instance with key equals to person name, i.e.:

Dictionary<string, Person> list;

Then you can get person by it's name, complexity is O(1)

if(list.ContainsKey(line[0]))
{
    list[line[0]]...
}

or even better:

Person p;

if(list.TryGetValue(line[0], out p))
{
    p...
)

回答2:

As of .NET Framework 4.7.2 there is TryGetValue method available for SortedSet.

回答3:

It is not possible to get an element from SortedSet or HashSet collections (using the Contains method or somehow else). One can just get to know whether the collection contains the element. Since in order to find this element in the collection, one already uses this element (passing it to the Contains method), it can be assumed that one already has this element.

回答4:

You may want to consider using the PowerCollections project — it has a lot of useful improvements to the standard generic collections.

来源：https://stackoverflow.com/questions/19556966/c-sharp-sortedset-how-to-get-an-element-out

标签

.net

sortedset