Question

i just want to know how to list all panel objects without using for each loop and to prevent recursive procedure..

Answer 1

In C#:

form.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance).
Where(fi => fi.FieldType.Equals(typeof(Panel)))

I used reflection since you wrote you don’t want recursive method, however not all panels in your form can be discovered like that. If you create your panels without define a class member (this could be done even in the designer), you won’t get it with this method.

Recursive method:

Panel[] GetPanels(Control container)
{
    List<Panel> panels = new List<Panel>();
    foreach (Control child in container.Controls)
    {
       if (child is Panel)
            panels.Add(child as Panel);
       panels.AddRange(GetPanels(child));
    }
    return panels.ToArray();
}

EDIT:
The above method is not optimized. It is creating too many lists and can’t be used as “lazy”. Here is another improved version:

IEnumerable<Panel> GetPanelsLazy(Control container)
{
    foreach (Control child in container.Controls)
    {
        if (child is Panel)
            yield return child as Panel;

        foreach (var panel in GetPanelsLazy(child))
        {
            yield return panel;
        }                
    }
}