How do you concatenate Lists in C#?

Question

If I have:

List myList1;
List myList2;

myList1 = getMeAList();
// Checked myList1, it contains 4 strings

myList2 = getMeAnother         


        

Answer 1

It also worth noting that Concat works in constant time and in constant memory. For example, the following code

        long boundary = 60000000;
        for (long i = 0; i < boundary; i++)
        {
            list1.Add(i);
            list2.Add(i);
        }
        var listConcat = list1.Concat(list2);
        var list = listConcat.ToList();
        list1.AddRange(list2);

gives the following timing/memory metrics:

After lists filled mem used: 1048730 KB
concat two enumerables: 00:00:00.0023309 mem used: 1048730 KB
convert concat to list: 00:00:03.7430633 mem used: 2097307 KB
list1.AddRange(list2) : 00:00:00.8439870 mem used: 2621595 KB