C# datagridview文本框列的逗号分隔符

我需要货币文本框在DataGridView，我搜索互联网，找到这个解决方案 但这在dataGridView单元格离开事件时很有用，我需要textchange中的逗号分隔符， 然而，我写这篇文章是为了这个目的：

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
        {
            TextBox txt_edit = e.Control as TextBox;
            if (txt_edit != null)
            {

                txt_edit.TextChanged += new EventHandler(txt_edit_TextChanged);
            }
        }

        private void txt_edit_TextChanged(object sender, EventArgs e)
        {
            TextBox txt = (TextBox) sender;

            string str = txt.Text;
            str = str.Replace(",", "");
            int len = str.Length;
            if (len > 3)
            {
                str = str.Insert(len - 3, ",");
                len = len - 3;
                while (len > 3)
                {
                    str = str.Insert(len - 3, ",");
                    len = len - 3;
                }
            }

            dataGridView1.EndEdit();
            dataGridView1.CurrentRow.Cells[0].Value = str;
            dataGridView1.BeginEdit(false);
        }

当我运行我的程序并输入数字时，该源正确地工作了3个第一位数字，直到键入第四个数字，并记录此错误：

为什么会出现这种错误？ 有没有更好的办法来解决这个问题？ tnx

这应该有效……（不是100%确定）

替换此项：

dataGridView1.EndEdit();
dataGridView1.CurrentRow.Cells[0].Value = str;
dataGridView1.BeginEdit(false);

与：

dataGridView1.EndEdit();
dataGridView1.CurrentRow.Cells[0].Value = str;
dataGridView1.BeginEdit(false);

int selStartFromEnd = txt.Text.Length - txt.SelectionStart;
txt.TextChanged -= txt_edit_TextChanged;
txt.Text = str;
txt.TextChanged += txt_edit_TextChanged;
if (txt.Text.Length - selStartFromEnd >= 0)
    txt.SelectionStart = txt.Text.Length - selStartFromEnd;
dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit);