C# Combobox dropdownlist item type

Question

I have a form with sixteen combo-boxes, each with the DropDownStyle property set to DropDownList. I am trying to set the form so each control shows its first pre-defined value:

    private void Form1_Load(object sender, EventArgs e)
    {
        foreach (ComboBox DropDown in this.Controls.OfType<ComboBox>())
            DropDown.SelectedIndex = 0;
    }

This code is not working, although individually assigning each item does. Any ideas why?

Answer 1

My WinForm experience is a bit rusty, but if I remember correctly, this.Controls will only bring you those controls directly under the main Form. If you have any subcontrols, like a Groupbox, they will be under that groupbox's .Controls.

You can either explicitly iterate your Groupbox's controls, or you can use recursion to go over all child controls of the form, like you can see here.