C# datagridview 验证输入时的信息

 private void dgvThrowDetails_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
        {
            if (dgvThrowDetails.CurrentCell != null)
            {
                switch (dgvThrowDetails.CurrentCell.OwningColumn.Name)
                {
                    case "SingleWeight":
                    case "Num":
                    case "Weight":
                    case "SinglePrice":
                    case "MinPrice":
                    case "CutLength":
                    case "PackingNum":
                        dgvTxt = (DataGridViewTextBoxEditingControl)e.Control;
                        dgvTxt.SelectAll();
                        dgvTxt.KeyPress -= new KeyPressEventHandler(Cells_KeyPress);
                        dgvTxt.KeyPress += new KeyPressEventHandler(Cells_KeyPress);
                        break;
                }

            }
        }

        private void Cells_KeyPress(object sender, KeyPressEventArgs e)
        {
            keyPressXS(e, dgvTxt);
        }

        private void keyPressXS(KeyPressEventArgs e, DataGridViewTextBoxEditingControl dgvTxt)
        {
            if (char.IsNumber(e.KeyChar) || e.KeyChar == '.' || e.KeyChar == (char)Keys.Back)
            {
                e.Handled = false;       //让操作生效
                int j = 0;
                int k = 0;
                bool flag = false;
                if (dgvTxt.Text.Length == 0)
                {
                    if (e.KeyChar == '.')
                    {
                        e.Handled = true;             //让操作失效
                    }
                }
                for (int i = 0; i < dgvTxt.Text.Length; i++)
                {
                    if (dgvTxt.Text[i] == '.')
                    {
                        j++;
                        flag = true;
                    }
                    if (flag)
                    {
                        if (char.IsNumber(dgvTxt.Text[i]) && e.KeyChar != (char)Keys.Back)
                        {
                            k++;
                        }
                    }
                    if (j >= 1)
                    {
                        if (e.KeyChar == '.')
                        {
                            e.Handled = true;             //让操作失效
                        }
                    }
                    if (k == 7)
                    {
                        if (char.IsNumber(dgvTxt.Text[i]) && e.KeyChar != (char)Keys.Back)
                        {
                            if (dgvTxt.Text.Length - dgvTxt.SelectionStart < 3)
                            {
                                if (dgvTxt.SelectedText != dgvTxt.Text)
                                {
                                    e.Handled = true;             ////让操作失效
                                }
                            }
                        }
                    }
                }
            }
            else
            {
                e.Handled = true;
            }
        }