Check if a ComboBox value is selected

Question

I'm writing a form which includes some buttons and a combo box. The "Ok" button is disabled by default, and I wish to enable it only after an actual value (not the combo box's name) is selected.

I know how to access the selected value, and how to check if a value has been selected - but these two can be done only after the form is close (using the"x" or using the "ok" button - which is disabled).

Any ideas?

Thanks.

Answer 1

Perhaps like this:

    private void comboBox_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (comboBox.SelectedIndex > -1)
        {
            buttonOK.Enabled = true;
        }
    }

By default a combobox's selected index is -1 (the combobox's name, which you can't reselect after choosing another index), so if you check that it's not -1 then you know a value has been selected.

However another alternative, and the one I use, is if I always want a value to be selected is to use the DropDownStyle property and set it to DropDownList. That way index 0 is selected by default and the user can only select items from the list and nothing else.