IEnumerable foreach, do something different for the last element

Question

I have an IEnumerable. I want to do one thing for each item of the collection, except the last item, to which I want to do something else. How can I code this neatly? I

Answer 1

Similar to Marc's answer, but you could write an extension method to wrap it up.

public static class LastEnumerator
{
    public static IEnumerable> GetLastEnumerable(this IEnumerable blah)
    {
        bool isFirst = true;
        using (var enumerator = blah.GetEnumerator())
        {
            if (enumerator.MoveNext())
            {
                bool isLast;
                do
                {
                    var current = enumerator.Current;
                    isLast = !enumerator.MoveNext();
                    yield return new MetaEnumerableItem
                        {
                            Value = current,
                            IsLast = isLast,
                            IsFirst = isFirst
                        };
                    isFirst = false;
                } while (!isLast);
            }
        }

    }
}

public class MetaEnumerableItem
{
    public T Value { get; set; }
    public bool IsLast { get; set; }
    public bool IsFirst { get; set; }
}

Then call it like so:

foreach (var row in records.GetLastEnumerable())
{
    output(row.Value);
    if(row.IsLast)
    {
        outputLastStuff(row.Value);
    }
}