Question

I am trying to raise an exception if a user clicks the delete button but doesn’t select a item in the listbox.

This is what I have:

try
{
    if (dataListBox.SelectedIndex == null)
        throw new Exception;

    //deletes selected items
    dataListBox.Items.RemoveAt(dataListBox.SelectedIndex);
    isDirty = true;
}
catch (Exception err)
{
    //spits out the errors if there are any
    MessageBox.Show(err.Message, "Enter something into the txtbox", MessageBoxButtons.OK, MessageBoxIcon.Error);
}

Answer 1

Use

SelectedIndex == -1

to know that nothing is selected.