How do I create a single list of object pairs from two lists in C#?

Question

I have two lists of objects. List A and List B. I need to create List C which combines List A and List B into pairs. For example:

List A
object a1
object a2
         


        

Answer 1

This would do it:

public static IEnumerable> CombineWith(this IEnumerable first, IEnumerable second)
{
    using (var firstEnumerator = first.GetEnumerator())
    using (var secondEnumerator = second.GetEnumerator())
    {
        bool hasFirst = true;
        bool hasSecond = true;

        while (
            // Only call MoveNext if it didn't fail last time.
            (hasFirst && (hasFirst = firstEnumerator.MoveNext()))
            | // WARNING: Do NOT change to ||.
            (hasSecond && (hasSecond = secondEnumerator.MoveNext()))
            )
        {
            yield return Tuple.Create(
                    hasFirst ? firstEnumerator.Current : default(T),
                    hasSecond ? secondEnumerator.Current : default(U)
                );
        }
    }
}

Edit: I vastly prefer Paul's answer.