c# - How to compare 2 List<string> objects to get the missing value from the List<string>

Question

How do I use the "NOT IN" to get the missing data, to be added to "foo" List.

var accessories = new List<string>(); 
var foo = new List<string>();

accessories.Add("Engine");
accessories.Add("Tranny");
accessories.Add("Drivetrain");
accessories.Add("Power Window");

foo.Add("Engine");
foo.Add("Tranny");
foo.Add("Power Window");

foreach(var v in foo.Where(x => x??).???)
{
    foo.Add(v);  //Add the missing "Drivetrain" to it...
}

Answer 1

You can use .Except() to get the difference between two sets:

var difference = accessories.Except(foo);
// difference is now a collection containing elements in accessories that are not in foo

If you then want to add those items to foo:

foo = foo.Concat(difference).ToList();