Question

I need to get all controls on a form that are of type x. I’m pretty sure I saw that code once in the past that used something like this:

dim ctrls() as Control
ctrls = Me.Controls(GetType(TextBox))

I know I can iterate over all controls getting children using a recursive function, but
is there something easier or more straightforward, maybe like the following?

Dim Ctrls = From ctrl In Me.Controls Where ctrl.GetType Is Textbox

Answer 1

Here’s another option for you. I tested it by creating a sample application, I then put a GroupBox and a GroupBox inside the initial GroupBox. Inside the nested GroupBox I put 3 TextBox controls and a button. This is the code I used (even includes the recursion you were looking for)

public IEnumerable<Control> GetAll(Control control,Type type)
{
    var controls = control.Controls.Cast<Control>();

    return controls.SelectMany(ctrl => GetAll(ctrl,type))
                              .Concat(controls)
                              .Where(c => c.GetType() == type);
}

To test it in the form load event I wanted a count of all controls inside the initial GroupBox

private void Form1_Load(object sender, EventArgs e)
{
    var c = GetAll(this,typeof(TextBox));
    MessageBox.Show("Total Controls: " + c.Count());
}

And it returned the proper count each time, so I think this will work perfectly for what you’re looking for 🙂