四则运算

private void Form1_Load(object sender, EventArgs e)
        {
            ReadXml();
            CreateExpressionAndResult();
        }

        protected override void OnClosing(CancelEventArgs e)
        {
            SaveXml();
            base.OnClosing(e);
        }

在程序启动的时候从sml文件中读取数据，设置一下难度，用户名等信息。

private void SaveXml()
        {
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(AppDomain.CurrentDomain.BaseDirectory + "Setting.xml");
            xmlDoc.RemoveAll();

            XmlElement xe = xmlDoc.CreateElement("saveData");
            xe.SetAttribute("userName", m_userName);
            xe.SetAttribute("difficulty", m_difficulty);
            xe.SetAttribute("totalCount", m_totalCount.ToString());
            xe.SetAttribute("correctCount", m_correctCount.ToString());

            xmlDoc.AppendChild(xe);
            xmlDoc.Save(AppDomain.CurrentDomain.BaseDirectory + "Setting.xml");
        }

        private void ReadXml()
        {
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(AppDomain.CurrentDomain.BaseDirectory + "Setting.xml");

            XmlElement xe = (XmlElement)xmlDoc.SelectSingleNode("saveData");
            m_userName = xe.GetAttribute("userName");
            m_difficulty = xe.GetAttribute("difficulty");
            m_totalCount = int.Parse(xe.GetAttribute("totalCount"));
            m_correctCount = int.Parse(xe.GetAttribute("correctCount"));
            m_wrongCount = m_totalCount - m_correctCount;

        }

 写入和读取xml文件的具体方法步骤

private void CreateExpressionAndResult()
        {
            m_expression = CalculateTest.Program.CreateExpression(m_difficulty);
            label1.Text = m_expression + " = ";
            m_result = CalculateTest.Program.Calculate(m_expression);   
        }

 用旧项中的方法生成表达式

private void button1_Click(object sender, EventArgs e)
        {
            string messageText;

            if (resultInput.Text == m_result.ToString())
            {
                messageText = "回答正确！";
                m_correctCount++;
            }
            else
            {
                messageText = "回答错误！正确答案是 " + m_result.ToString() ;
                m_wrongCount++;
            }

            m_totalCount++;
            DialogResult dr = MessageBox.Show(messageText, "提示：");

            if (dr == DialogResult.OK)
            {
                CreateExpressionAndResult();
                resultInput.Text = "";
            }
        }

弹出了一个提示用来显示回答是否是正确，而且能更新答题的总数，正确题数和错误的题数，晴空input并做下一道题目。

string m_userName
        {
            get
            {
                return userNameLabel.Text;
            }

            set
            {
                userNameLabel.Text = value;
            }
        }

        string m_difficulty
        {
            get
            {
                return difficultyLabel.Text;
            }

            set
            {
                difficultyLabel.Text = value;
            }
        }

        int m_totalCount
        {
            get
            {
                return int.Parse(totalCountLabel.Text);
            }

            set
            {
                totalCountLabel.Text = value.ToString();
            }
        }

        int m_correctCount
        {
            get
            {
                return int.Parse(correctCountLabel.Text);
            }

            set
            {
                correctCountLabel.Text = value.ToString();
            }
        }

        int m_wrongCount
        {
            get
            {
                return int.Parse(wrongCountLabel.Text);
            }

            set
            {
                wrongCountLabel.Text = value.ToString();
            }
        }

 通过变量的赋值来更新界面上所显示的内容。

if (difficulty == "Easy")
            {
                oplist = new List<char>() { '+', '-', '+', '-' };
            }
            else
            {
                oplist = new List<char>() { '+', '-', '*', '/' };
            }

 如果是简单的，就只有加减乘除。

if (difficulty == "Difficult")
            {
                int pos;
                index = expList.IndexOf("/");

                if (-1 == index)
                {
                    pos = position[ran.Next(3)];
                }
                else
                {
                    if (1 == index)
                    {
                        position.RemoveAt(1);
                    }
                    else if (3 == index)
                    {
                        position.RemoveAt(2);
                    }

                    pos = position[ran.Next(position.Count())];
                }

                expList.Insert(pos, "(");
                expList.Insert(pos + 4, ")");
            }

 难度是困难时，插入了括号，枚举括号的位置。

结对伙伴：李俞寰