我正在嘗試制作一個計算器并且想知道如何修復錯誤（我是C#或任何編程語言的新手）

所以基本上每當我嘗試更改 while 回圈內的變數“restart”時，它都會給我一個錯誤，提示“無法在此范圍內宣告名為 'restart' 的本地或引數，因為該名稱用于封閉的本地范圍來定義本地或引數”。如果有人知道如何解決這個問題，請告訴我

public class Program
{
    public static void Main()
    {
        bool restart = true;
        while (restart == true)
        {
            Console.WriteLine("please enter Multiply, Divide, Add Or Subtract");
            string Method = Console.ReadLine();
            if (Method == "Add")
            {
                Console.WriteLine("Please Enter First Number");
                double numberOne = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine("Please Enter The Second Number");
                double numberTwo = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine(numberOne   numberTwo);
                Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
                bool restart = Convert.ToBoolean(Console.ReadLine());
            }
            else if (Method == "Subtract")
            {
                Console.WriteLine("Please Enter First Number");
                double numberOne = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine("Please Enter The Second Number");
                double numberTwo = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine(numberOne - numberTwo);
                Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
                bool restart = Convert.ToBoolean(Console.ReadLine());
            }
            else if (Method == "Multiply")
            {
                Console.WriteLine("Please Enter First Number");
                double numberOne = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine("Please Enter The Second Number");
                double numberTwo = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine(numberOne * numberTwo);
                Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
                bool restart = Convert.ToBoolean(Console.ReadLine());
            }
            else if (Method == "Divide")
            {
                Console.WriteLine("Please Enter First Number");
                double numberOne = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine("Please Enter The Second Number");
                double numberTwo = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine(numberOne / numberTwo);
                Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
                bool restart = Convert.ToBoolean(Console.ReadLine());
            }
            else
            {
                Console.WriteLine("error found");
                Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
                bool restart = Convert.ToBoolean(Console.ReadLine());
            }
        }
    }
}```

uj5u.com熱心網友回復：

讓我們看一下您的代碼的這一部分：

bool restart = true;
while (restart == true)
{
    // Some stuff omitted...
    bool restart = Convert.ToBoolean(Console.ReadLine());
}

你重新申報 restart。相反，您應該像這樣分配它（bool在首次宣告后使用變數時不要使用）：

restart = Convert.ToBoolean(Console.ReadLine());

uj5u.com熱心網友回復：

你需要這樣的東西：

    bool restart = true;
    while (restart)
    {
        Console.WriteLine("please enter Multiply, Divide, Add Or Subtract");
        string method = Console.ReadLine();
        if (new[] { "Multiply", "Divide", "Add", "Subtract" }.Contains(method))
        {
            Console.WriteLine("Please Enter First Number");
            double numberOne = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("Please Enter The Second Number");
            double numberTwo = Convert.ToDouble(Console.ReadLine());
            if (method == "Add")
            {
                Console.WriteLine(numberOne   numberTwo);
            }
            else if (method == "Subtract")
            {
                Console.WriteLine(numberOne - numberTwo);
            }
            else if (method == "Multiply")
            {
                Console.WriteLine(numberOne * numberTwo);
            }
            else if (method == "Divide")
            {
                Console.WriteLine(numberOne / numberTwo);
            }
            Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
            restart = Convert.ToBoolean(Console.ReadLine());
        }
        else
        {
            Console.WriteLine("error found");
            Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
            restart = Convert.ToBoolean(Console.ReadLine());
        }
    }

或這個：

    Dictionary<string, Func<double, double, double>> operations =
        new Dictionary<string, Func<double, double, double>>()
        {
            { "Add", (x, y) => x   y },
            { "Subtract", (x, y) => x - y },
            { "Multiply", (x, y) => x * y },
            { "Divide", (x, y) => x / y },
        };
    
    bool restart = true;
    while (restart)
    {
        Console.WriteLine($"Please enter one of: {String.Join(", ", operations.Keys)}");
        string method = Console.ReadLine();
        if (operations.ContainsKey(method))
        {
            Console.WriteLine("Please Enter First Number");
            double numberOne = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("Please Enter The Second Number");
            double numberTwo = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine(operations[method](numberOne, numberTwo));
        }
        else
        {
            Console.WriteLine("error found");
        }
        Console.WriteLine("Would You Like To Use The Calculator Again? (true = yes, false = no)");
        restart = Convert.ToBoolean(Console.ReadLine());
    }

標籤：C＃ while 循环 计算器

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