首先绑定keypresss事件。然后调用这句话就ok了

   private static bool verifyFloatNumberInputPressCallBack(object sender, KeyPressEventArgs e)
        {
            string text = ((TextBox)sender).Text;
            if (e.KeyChar == '\b')
            {
                LogUtil.writeLog("退格键");
                return false;
            }
            if (!Char.IsDigit(e.KeyChar) && e.KeyChar != '.')
            {
                e.Handled = true;//不合法
                LogUtil.writeLog("非数字键也不是小数点，忽略");
                return false;
            }
            text = text.Insert((int)text.Length, e.KeyChar.ToString() + "0");
            LogUtil.writeLog("input {0}", text);
            if (!RegHelper.isNumber(text) && e.KeyChar != '\b' && text != "")
            {
                LogUtil.writeLog("不合法");
                e.Handled = true;//不合法
                return false;
            }

            return true;

        }