c# Adding a Remove(int index) method to the .NET Queue class

Question

I would like to use the generic queue class as described in the .NET framework (3.5) but I will need a Remove(int index) method to remove items from the queue. Can I achieve

Answer 1

Although there isn't a built-in way, you shouldn't use a List structure or other structure, IFF RemoveAt isn't a frequent operation.

If you are normally enqueuing and dequeuing but only occasionally removing, then you should be able to afford a queue rebuild when removing.

public static void Remove(this Queue queue, T itemToRemove) where T : class
{
    var list = queue.ToList(); //Needs to be copy, so we can clear the queue
    queue.Clear();
    foreach (var item in list)
    {
        if (item == itemToRemove)
            continue;

        queue.Enqueue(item);
    }
}

public static void RemoveAt(this Queue queue, int itemIndex) 
{
    var list = queue.ToList(); //Needs to be copy, so we can clear the queue
    queue.Clear();

    for (int i = 0; i < list.Count; i++)
    {
        if (i == itemIndex)
            continue;

        queue.Enqueue(list[i]);
    }
}

The following approach might be more efficient, using less memory, and thus less GC:

public static void RemoveAt(this Queue queue, int itemIndex)
{
    var cycleAmount = queue.Count;

    for (int i = 0; i < cycleAmount; i++)
    {
        T item = queue.Dequeue();
        if (i == itemIndex)
            continue;

        queue.Enqueue(item);
    }
}