oop - How do i convert a List<Interface> to List<Class> in c#

Question

I have an interface defined as

public interface IReaderInfo
{
    string Displayname {get;}
}

and a class that implements that interface

public class ReaderInfo : IReaderInfo
{
    string DisplayName {get;}
}

I then created a function which return List

public List<ReaderInfo> GetReaders
{
     var readers = new List<ReaderInfo>();
     var Ireaders = someobject.Getreaders();// Returns the list of IReaderInfo.
     // Now i would like cast Ireaders as readers and return.
}

How do i cast it?

Answer 1

You have to create a new list with casted items:

var readers = Ireaders.Cast<ReaderInfo>().ToList();

Or, if there is a possibility to have incompatible IReaderInfo entries and you only want the actual ReaderInfo objects in the result:

var readers = Ireaders.OfType<ReaderInfo>().ToList();