How to use a List and LINQ

Asked May 19 '17 at 21:42

Active May 19 '17 at 23:04

Viewed 49 times

I have the following interface and classes and I get an error saying "Cannot implicitly convert World to IWord...". Thank you for any help:

public interface IWord
{

}

public class Word : IWord
{

}

public class MyTest
{
    public IList<IWord> GetAll()
    {
        // I fixed, there is any better way?
        var list data.Where(x => x.Value == n).Select(o => new Word(o.Value, o.Key)).Cast<IWord>().ToList();
        return list;
    }
}

edited May 19 '17 at 23:04

asked May 19 '17 at 21:42

Doro

1

You need to change `List` to `List` – Rufus L May 19 '17 at 21:46
2

Read up on [covariance and contravariance](https://msdn.microsoft.com/en-us/library/dd799517(v=vs.110).aspx). Essentially you cannot cast a `List` to an `IList` because the latter could accept a `NewWord : IWord` but the former could not. – Brad May 19 '17 at 21:46
Well, my actually code uses a LINQ expression. Please see my update – Doro May 19 '17 at 22:04
1

remove `ToList()` from LINQ, then `return new List(linq_result);` – Ben Voigt May 19 '17 at 22:13
@BenVoigt, it worked! – Doro May 19 '17 at 22:16

How to use a List and LINQ

0 Answers0