Foreach loop, determine which is the last iteration of the loop

Question

I have a foreach loop and need to execute some logic when the last item is chosen from the List, e.g.:

 foreach (Item result in Mod         


        

Answer 1

Improving Daniel Wolf answer even further you could stack on another IEnumerable to avoid multiple iterations and lambdas such as:

var elements = new[] { "A", "B", "C" };
foreach (var e in elements.Detailed())
{
    if (!e.IsLast) {
        Console.WriteLine(e.Value);
    } else {
        Console.WriteLine("Last one: " + e.Value);
    }
}

The extension method implementation:

public static class EnumerableExtensions {
    public static IEnumerable> Detailed(this IEnumerable source)
    {
        if (source == null)
            throw new ArgumentNullException(nameof(source));

        using (var enumerator = source.GetEnumerator())
        {
            bool isFirst = true;
            bool hasNext = enumerator.MoveNext();
            int index = 0;
            while (hasNext)
            {
                T current = enumerator.Current;
                hasNext = enumerator.MoveNext();
                yield return new IterationElement(index, current, isFirst, !hasNext);
                isFirst = false;
                index++;
            }
        }
    }

    public struct IterationElement
    {
        public int Index { get; }
        public bool IsFirst { get; }
        public bool IsLast { get; }
        public T Value { get; }

        public IterationElement(int index, T value, bool isFirst, bool isLast)
        {
            Index = index;
            IsFirst = isFirst;
            IsLast = isLast;
            Value = value;
        }
    }
}