如何从DataTable中将Last（）作为IEnumerable返回

Question

How do I return Last() as an IEnumerable from a DataTable?

I want IEnumerable because I may pass in a larger subset of rows.

public static void Set(IEnumerable<DataRow> rowsToProcess)
{
    //Do something with rowsToProcess;
}

DataTable data;

//This works:
Set(Data.AsEnumerable());

//This gives an error:
Set(Data.AsEnumerable().Last());

Cannot convert from DataRow to IEnumerable<DataRow>

Answer 1

You could put it in an array:

Set(new[]{ Data.AsEnumerable().Last() });

or you could use this:

Set(Data.AsEnumerable().Reverse().Take(1));

or this:

Set(Data.AsEnumerable().Skip(Data.Rows.Count - 1));

this non-LINQ approach is probably the most efficient way, because it avoids a loop:

Set(new[]{ Data.Rows[Data.Rows.Count-1] });

---

For what it's worth, you could also use following extension ;-)

public static IEnumerable<T> AsSequence<T>(this T obj)
{
    yield return obj;
}  

...

Set(Data.AsEnumerable().Last().AsSequence());