Is there a way to convert a List(of Object) to a List(of String) in c# or vb.net without iterating through all the items? (Behind the scenes iteration is fine – I just want concise code)
Update: The best way is probably just to do a new select
myList.Select(function(i) i.ToString()).ToList();
or
myList.Select(i => i.ToString()).ToList();
Not possible without iterating to build a new list. You can wrap the list in a container that implements IList.
You can use LINQ to get a lazy evaluated version of IEnumerable<string> from an object list like this:
var stringList = myList.OfType<string>();
List<object> that contains string objects only and you want to get a List<string> of those objects instead. The question is unclear about what the input is; depending on the input specification and your goal, you may want to pick OfType<string>, Cast<string>(), or Select(...).This works for all types.
List<object> objects = new List<object>();
List<string> strings = objects.Select(s => (string)s).ToList();
If you want more control over how the conversion takes place, you can use ConvertAll:
var stringList = myList.ConvertAll(obj => obj.SomeToStringMethod());
You mean something like this?
List<object> objects = new List<object>();
var strings = (from o in objects
select o.ToString()).ToList();
var userIDsSource = (from r in MigrationSession.UsersSource select r.UserID).ToList();List<string> myList Str = myList.Select(x=>x.Value).OfType<string>().ToList();
Use "Select" to select a particular column
No - if you want to convert ALL elements of a list, you'll have to touch ALL elements of that list one way or another.
You can specify / write the iteration in different ways (foreach()......, or .ConvertAll() or whatever), but in the end, one way or another, some code is going to iterate over each and every element and convert it.
Marc
Can you do the string conversion while the List(of object) is being built? This would be the only way to avoid enumerating the whole list after the List(of object) was created.
