Finding all controls in an ASP.NET Panel?

It boils down to enumerating all the controls in the control hierarchy:

    IEnumerable<Control> EnumerateControlsRecursive(Control parent)
    {
        foreach (Control child in parent.Controls)
        {
            yield return child;
            foreach (Control descendant in EnumerateControlsRecursive(child))
                yield return descendant;
        }
    }

You can use it like this:

        foreach (Control c in EnumerateControlsRecursive(Page))
        {
            if(c is TextBox)
            {
                // do something useful
            }
        }

You can loop thru the panels controls

foreach (Control c in MyPanel.Controls) 
{
   if (c is Textbox) {
        // do something with textbox
   } else if (c is Checkbox) {
        /// do something with checkbox
   }
}

If you have them nested inside, then you'll need a function that does this recursively.