Is it possible to iterate over two IEnumerable objects at the same time?

Question

If I have a List(Of x) and a List(Of y) is it possible to iterate over both at the same time?

Something like

for each _x as X, _y as Y in List(of x         


        

Answer 1

I'm not very proficient in VB.NET, but here's an extension method in C# you can create to do this. I hope you can port it!

public static class IEnumExtensions
{
    public static IEnumerable<KeyValuePair<T, U>> EnumTwoCollections<T, U>(this IEnumerable<T> list1, IEnumerable<U> list2)
    {
        var enumerator1 = list1.GetEnumerator();
        var enumerator2 = list2.GetEnumerator();

        bool moveNext1 = enumerator1.MoveNext();
        bool moveNext2 = enumerator2.MoveNext();

        while (moveNext1 || moveNext2)
        {

            T tItem = moveNext1 ? enumerator1.Current : default(T);
            U uItem = moveNext2 ? enumerator2.Current : default(U);

            yield return new KeyValuePair<T, U>(tItem, uItem);

            moveNext1 = enumerator1.MoveNext();
            moveNext2 = enumerator2.MoveNext();
        }
    }
}

Usage:

    List<int> intList = new List<int>();
    List<string> stringList = new List<string>();
    for (int i = 1; i <= 10; i++)
    {
        intList.Add(i);
        stringList.Add((i * i).ToString());
    }

    foreach (var items in intList.EnumTwoCollections(stringList))
    {
        Console.WriteLine(items.Key + " , " + items.Value);
    }

Noticed now that you're not using .NET 3.5 so you probably can't use extension methods either. Just put this in some helper class and you can call it like this:

foreach(KeyValuePair<int,string> kvp in Helper.EnumTwoCollections(intList,stringList))
{
...
}