Winform ComBox模糊查询

List<string> list = new List<string>();
            list.Add("张三");
            list.Add("李四");
            list.Add("王五");
            list.Add("老王");

            comboBox1.Items.AddRange(list.ToArray());

 private void comboBox1_TextUpdate(object sender, EventArgs e)
        {
            List<string> listNew = new List<string>();
            comboBox1.Items.Clear();
            string str = comboBox1.Text;
            foreach (var item in list)
            {
                if (item.Contains(str))
                {
                    listNew.Add(item);
                }
            }
            comboBox1.Items.AddRange(listNew.ToArray());
            comboBox1.SelectionStart = comboBox1.Text.Length;
            Cursor = Cursors.Default;
            this.comboBox1.DroppedDown = true;//自动展开下拉框
        }