Flatten a list in linq

Question

Let's assume my list is like this:

List<List<string>> zz = new List<List<string>>() { new List<string>{"1","2","3"}, new List<string> { "4", "5", "6" } };

I want one list as output as follows:

List<string> finalList = new List<string>{"1","2","3","4", "5", "6"};

How do I flatten to this?

Answer 1

You can use SelectMany

var finalList = zz.SelectMany(x=>x).ToList();

Answer 2

var finalList = zz.SelectMany(a => a).ToList();