C# (CSharp) increment items примеры использования

Пример #1

        private void Btn_delete_Click(object sender, RoutedEventArgs e)
        {
            items st = (items)gridData.SelectedItem;

            prod.Remove(st);
        }

Пример #2

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            items st = (items)gridData.SelectedItem;

            st.quantity++;
        }