namespace winform1
    {
        public class OurComBox : System.Windows.Forms.ComboBox
        {
            //==============overwrite ComboBox OnkeyUp method
            protected override void OnKeyUp(System.Windows.Forms.KeyEventArgs e)
            {
                foreach (object item in this.Items)
                {
                    string[] strs = item.ToString().Split("-".ToCharArray());//利用空格来分格字符串
                    if (strs[0].Trim().Equals(this.Text))//如果输入的值等于前面的编号
                    {
                        this.SelectedItem = item;
                        this.SelectAll();
                    }
                }
                base.OnKeyUp(e);
            }
            //=================
        }
    }