IEqualityComparer not working as intended

Question

I have a List of paths of files stored on my computer. My aim is to first filter out the files which have the same name and and then filter out those which have

Answer 1

Your GetHashCode must return the same value for any objects that are of equal value:

// Try this
public int GetHashCode(string obj)
{
    return Path.GetFileName(x).GetHashCode();
}

// And this
public int GetHashCode(string obj)
{
    return new FileInfo(x).Length.GetHashCode();
}

But this is a much easier way for the whole problem without the extra classes:

var query = FilesList
                .GroupBy(f => Path.GetFileName(f)).Select(g => g.First())
                .GroupBy(f => new FileInfo(f).Length).Select(g => g.First())
                .ToList();