詳細介紹C#數學運算運算式解譯器的範例程式碼

C#數學運算運算式解譯器

測試檔案內容：

a=2+3*2;b=2*(2+3);

瀏覽按鈕事件處理常式：

        private void button_browse_Click(object sender, EventArgs e)
        {
            OpenFileDialog fbd = new OpenFileDialog();
            fbd.Title = "請選擇一個檔案：";
            fbd.CheckFileExists = true;
            fbd.CheckPathExists = true;
            fbd.Filter = "*.txt(文字檔)|*.txt|*.*(所有檔案)|*.*";
            fbd.FileName = Environment.GetFolderPath(Environment.SpecialFolder.MyComputer);
            if (fbd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                textBox_saveDir.Text = fbd.FileName;
                try
                {
                    FileStream fs = new FileStream(fbd.FileName, FileMode.Open, FileAccess.Read);
                    StreamReader sr = new StreamReader(fs);
                    while (!sr.EndOfStream)
                    {
                        string line = sr.ReadLine();
                        analyse(line);
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show("錯誤：" + ex.Message + "\r\n堆棧：" + ex.StackTrace);
                }
            }
        }

分析一行運算式：

        private void analyse(string line)        {            //以分號作為結束符，支援一行內寫多個語句            string[] expA = line.Split(new string[] { ";" }, StringSplitOptions.RemoveEmptyEntries);            for (int i = 0; i < expA.Length; i++)            {                analyseExpA(expA[i]);            }        }

計算一條運算式：

        private void analyseExpA(string expA)        {            string[] expB = expA.Split(new string[] { "=" }, StringSplitOptions.RemoveEmptyEntries);            for (int i = 0; i < expB.Length; i++ )            {                Regex reg = new Regex("[a-zA-Z]");                if (!reg.IsMatch(expB[i]))                {                    object obj = EvalExpress(expB[i]);                    if (obj != null)                    {                        textBox1.Text += expA + " = " + obj.ToString() + "\r\n";                    }                    else                    {                        textBox1.Text += expA + ",無法識別的運算式\r\n";                    }                }            }        }