Question

var listOne = new string[] { "dog", "cat", "car", "apple"};
var listTwo = new string[] { "car", "apple"};

What I need is to order listOne by the order of items in listTwo (if present). So the new list would be in this order;
“car”, “apple”, “dog”, “cat”

I would like to do this in LINQ and have tried this;

var newList = from l1 in listOne
              join l2 in listTwo on l1 equals l2 in temp
              from nl temp.DefaultIfEmpty()
              select nl;

But it returns null so evidently my Linq-Fu is weak. Any advise is appreciated.

Answer 1

You need all the items from listTwo that are in listOne followed by the remaining items from listOne?

var results = listTwo.Intersect(listOne).Union(listOne);
foreach (string r in results)
{
    Console.WriteLine(r);
}