C# c中循环时的无穷大#

我是c#的新手，在while循环中遇到了一个无法中断的问题。这只是一个简单的控制台计算器，如果输入正确，我希望switch语句脱离循环，否则继续循环。问题是，即使选择了正确的字母，它也会继续循环，例如a作为add，下面是我的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace basic_calc
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("this is a basic calculator");
            double num1 = Getvalue("Enter the first number: ");
            double num2 = Getvalue("Enter the second number: ");

            double output = 0;
            while (true)
            {
                Console.WriteLine(" Please select an operation (A)dd, (S)ubtract, (M)ultiply, (D)ivide");
                char operation = Console.ReadKey().KeyChar;
                operation = Char.ToUpper(operation);
                switch (operation)
                {
                    case 'A':
                        output = Add(num1, num2);
                        break;
                    case 'S':
                        output = Subtract(num1, num2);
                        break;
                    case 'M':
                        output = Multiply(num1, num2);
                        break;
                    case 'D':
                        output = Divide(num1, num2);
                        break;
                    default:
                        Console.ForegroundColor = ConsoleColor.Red;
                        Console.WriteLine("INVALID INPUT!!!!!!!!!!!!!!!");
                        Console.ResetColor();
                        continue;
                }    
            }


            Console.WriteLine("\nresult: "+ output);

            Console.ReadKey();
        }
        private static double Getvalue(string input)
        {
            //the value to be returned
            double value;
            while (true)
            {
                Console.Write(input);
                string number = Console.ReadLine();
                if (double.TryParse(number, out value))
                {
                    return value;

                }
                else
                    Console.WriteLine("please enter a number for this calculator");
            }
        }
        private static double Add(double n1, double n2){return n1 + n2;}
        private static double Subtract(double n1, double n2) { return n1 - n2; }
        private static double Multiply(double n1, double n2) { return n1 * n2; }
        private static double Divide(double n1, double n2) { return n1 / n2; }
    }
}

---

只需在

开关

后添加一个

中断

：

switch (operation)
{
    case 'A':
        output = Add(num1, num2);
        break;
    case 'S':
        output = Subtract(num1, num2);
        break;
    case 'M':
        output = Multiply(num1, num2);
        break;
    case 'D':
        output = Divide(num1, num2);
        break;
    default:
        Console.ForegroundColor = ConsoleColor.Red;
        Console.WriteLine("INVALID INPUT!!!!!!!!!!!!!!!");
        Console.ResetColor();
        continue;
}
break; // This will exit the loop when a match is found.

---

由于您正在使用

continue

，如果未找到匹配项，则

开关

后的

中断

将在找到匹配项时退出循环。

您的

中断

只是跳出开关语句。使用您在案例中设置的bool变量进行尝试：

var noOutput = true;
while (noOutput)
            {
                Console.WriteLine(" Please select an operation (A)dd, (S)ubtract, (M)ultiply, (D)ivide");
                char operation = Console.ReadKey().KeyChar;
                operation = Char.ToUpper(operation);
                switch (operation)
                {
                    case 'A':
                        output = Add(num1, num2);
                        noOutput = false;
                        break;
                    ...
                }    
            }

---

您必须中断switch语句。由于

While（true）

您最终进入了一个循环。因此，在switch语句之后，将出现

中断

switch (operation)
{
case 'A':
    output = Add(num1, num2);
    break;
case 'S':
    output = Subtract(num1, num2);
    break;
case 'M':
    output = Multiply(num1, num2);
    break;
case 'D':
    output = Divide(num1, num2);
    break;
default:
    Console.ForegroundColor = ConsoleColor.Red;
    Console.WriteLine("INVALID INPUT!!!!!!!!!!!!!!!");
    Console.ResetColor();
    continue;
}
  break; 

while（true）

不是可读/明显（因此是可维护和可调试的（以合理的方式））代码的好标志。虽然你有你的答案，但我还是会用这种方式做事。