Question

用C语言while 与 do while设计一个简单的计算器程序

该程序接收用户从键盘输入的一个无括号简单表达式形式，以等号代表结束（运算符限定为+、-、*、/之一）。计算后表达式的值（默认所有运算符优先级相同，从左至右运算）并输出。

可能的输入输出示例：（较简形式）

输入： 22/5-3*2=

输出： 2.800000

Answer 1

      static void Main(string[] args)
        {
            Console.Write("输入计算式：");
            string sInput = Console.ReadLine();          
            System.Text.RegularExpressions.Regex regT =
                new System.Text.RegularExpressions.Regex(@"(?<be>\d+(\.\d+)?)(?<op>[+\-*/])(?<on>\d+(\.\d+)?)");
            System.Text.StringBuilder sbT = new StringBuilder(sInput);
            sbT.Replace(" ", "");
            System.Text.RegularExpressions.Match m = regT.Match(sbT.ToString());
            while (m.Success)
            {
                double dblBe = double.Parse(m.Groups["be"].ToString());
                double dblOn = double.Parse(m.Groups["on"].ToString());
                double dblR = 0;
                switch (m.Groups["op"].ToString())
                {
                    case "+":
                        dblR = dblBe + dblOn;
                        break;
                    case "-":
                        dblR = dblBe - dblOn;
                        break;
                    case "*":
                        dblR = dblBe * dblOn;
                        break;
                    case "/":
                        if (dblOn != 0)
                        {
                            dblR = dblBe / dblOn;
                        }
                        else
                        {
                            Console.WriteLine("除数不能为零");
                            Console.ReadKey();
                            System.Threading.Thread.CurrentThread.Abort();
                        }
                        break;
                }
                sbT.Replace(m.Value, string.Format("{0:G}", dblR), 0, m.Length);
                m = regT.Match(sbT.ToString());
            }
            Console.WriteLine("计算结果：" + sbT.ToString());
            Console.ReadKey();
        }