Question

I am looking for a very fast way to filter down a collection in C#. I am currently using generic List<object> collections, but am open to using other structures if they perform better.

Currently, I am just creating a new List<object> and looping thru the original list. If the filtering criteria matches, I put a copy into the new list.

Is there a better way to do this? Is there a way to filter in place so there is no temporary list required?

Answer 1

If you’re using C# 3.0 you can use linq, which is way better and way more elegant:

List<int> myList = GetListOfIntsFromSomewhere();  // This will filter ints that are not > 7 out of the list; Where returns an // IEnumerable<T>, so call ToList to convert back to a List<T>. List<int> filteredList = myList.Where(x => x > 7).ToList(); 

If you can’t find the .Where, that means you need to import using System.Linq; at the top of your file.