C# 計算器變量未重置

Question

計算器將運行並繼續進行相同的計算，直到您鍵入 stop 然后它將開始新的計算，但 num1 將保持上次計算中的最后一個值並且不會重置。

例子：

輸入數字 22

您要執行什么計算 +

輸入數字 33

答案 55

您要執行什么計算 /

輸入數字 5

答案 11

您要執行什么計算停止

輸入數字 2

您要執行什么計算 +

輸入數字 9

答案 20

      Boolean x;
        x = true;

        while (x == true)
        {
            double num1;
            double ans;
            double num2;
            string cal;
            Boolean y;
            y = true;

            Console.WriteLine("Enter a number ");
            num1 = Convert.ToInt32(Console.ReadLine());

            while (y == true)
            {

                Console.WriteLine("What calculation do you want to perform ");
                cal = Console.ReadLine();

                Console.WriteLine("Enter a number ");
                num2 = Convert.ToInt32(Console.ReadLine());

                switch (cal)
                {
                    case "+":
                        ans = add(num1, num2);
                        Console.WriteLine("Answer " + ans);
                        num1 = ans;
                        break;

                    case "-":
                        ans = sub(num1, num2);
                        Console.WriteLine("Answer " + ans);
                        num1 = ans;
                        break;

                    case "/":
                        ans = div(num1, num2);
                        Console.WriteLine("Answer " + ans);
                        num1 = ans;
                        break;

                    case "*":
                        ans = mul(num1, num2);
                        Console.WriteLine("Answer " + ans);
                        num1 = ans;
                        break;

                    case "Stop":
                        y = false;
                        break;
                }


            }
        }
    }

    private static double add(double firstnumber, double secondnumber)
    {
        double answer;
        answer = firstnumber + secondnumber;
        return answer;
    }
    private static double sub(double firstnumber, double secondnumber)
    {
        double answer;
        answer = firstnumber - secondnumber;
        return answer;
    }
    private static double div(double firstnumber, double secondnumber)
    {
        double answer;
        answer = firstnumber / secondnumber;
        return answer;
    }
    private static double mul(double firstnumber, double secondnumber)
    {
        double answer;
        answer = firstnumber * secondnumber;
        return answer;
    }

Answer 1

把它歸零

 case "Stop":
 y = false;
  num1=0;
   break;

Answer 2

該程序需要"Stop"作為cal的輸入以終止，但您輸入了"stop" 。 看到不同？

最好將輸入轉換為小寫

cal = Console.ReadLine().ToLower();

然后在 switch 語句中檢查它。 還要始終在 switch 中包含一個default分支，因為您需要預料到意外情況。

switch (cal)
{
    ..
    case "stop":
        y = false;
        break;
    default:
        // what happens if input is not +-*/ or stop?
        break;
}