If you have an interface like this
public interface IData
{
string Value { get; set; }
}
and a class implementing this interface
public class Data : IData
{
public string Value { get; set; }
}
and a list of Data like this
var dataList = new List<Data>
{
new Data {Value = "A"},
new Data {Value = "B"}
};
you could cast to IData like this:
var iDataList = dataList.Cast<IData>();