c#中switch语句的伪代码

Question

如何在 C# 中为 switch (case) 语句编写伪代码？

switch (option)
{
    case 1:
        Console.Write("Enter First Number: ");
        num1 = Convert.ToDouble(Console.ReadLine());

        Console.Write("Enter Second Number: ");
        num2 = Convert.ToDouble(Console.ReadLine());

        result = num1 + num2;
        Console.WriteLine(result);
        break;

    case 2:
        Console.Write("Enter First Number: ");
        num1 = Convert.ToDouble(Console.ReadLine());

        Console.Write("Enter Second Number: ");
        num2 = Convert.ToDouble(Console.ReadLine());

        result = num1 - num2;
        Console.WriteLine(result);
        break;

    case 3:
        Console.Write("Enter First Number: ");
        num1 = Convert.ToDouble(Console.ReadLine());

        Console.Write("Enter Second Number: ");
        num2 = Convert.ToDouble(Console.ReadLine());

        result = num1 * num2;
        Console.WriteLine(result);
        break;

    default:
        Console.WriteLine("\n Next time follow instructions. You can only choose numbers 1 - 4");
        break;
}

Answer 1

所以，如果我要写这个，我将从操作的枚举类型开始：

public enum ArithmeticOperation
{
    Add,
    Subtract,
    Multiply,
    Divide,
}

我会写一个小助手函数：

 private static string ShowEnumOptions<T>() where T : struct
 {
     if (!typeof(T).IsEnum)
     {
         throw new ArgumentException($"Type: {typeof(T).ToString()} must be an enumerated type");
     }

     var options = Enum.GetNames(typeof(T));
     return string.Join("/", options);
 }

（最新版本的 C#（我还没有使用）允许在泛型类型参数上使用 System.Enum 约束，这将简化这一点）

然后我会写我的主程序看起来像这样：

static void Main(string[] args)
{
    while (true)
    {
        ArithmeticOperation operation = default(ArithmeticOperation);
        var goodOperation = false;
        while (!goodOperation)
        {
            Console.Write(
                $"Enter operation (one of [{ShowEnumOptions<ArithmeticOperation>()}] or \"Quit\"): ");
            var response = Console.ReadLine();
            if (string.Equals(response, "Quit", StringComparison.InvariantCultureIgnoreCase))
            {
                return; //quit the app
            }

            if (Enum.TryParse<ArithmeticOperation>(response, true, out operation))
            {
                goodOperation = true;
            }
        }

        double value1 = 0.0;
        double value2 = 0.0;        //initialize them to keep the compiler happy
        var goodDouble = false;
        while (!goodDouble)
        {
            Console.Write("Enter the first number: ");
            var response = Console.ReadLine();
            if (double.TryParse(response, out value1))
            {
                goodDouble = true;
            }
        }
        goodDouble = false;
        while (!goodDouble)
        {
            Console.Write("Enter the second number: ");
            var response = Console.ReadLine();
            if (double.TryParse(response, out value2))
            {
                goodDouble = true;
            }
        }

        //ok, got an operation and two numbers

        double result = 0.0;
        switch (operation)
        {
            case ArithmeticOperation.Add:
                result = value1 + value2;
                break;
            case ArithmeticOperation.Subtract:
                result = value1 - value2;
                break;
            case ArithmeticOperation.Multiply:
                result = value1 * value2;
                break;
            case ArithmeticOperation.Divide:
                if (value2 == 0.0)
                {
                    Console.WriteLine("Division by zero is invalid");
                    result = double.NaN;   //NaN means "not a number"
                    break;
                }
                result = value1 / value2;
                break;
        }

        Console.WriteLine($"Result is {result}");
    }
}

请注意，我检查了所有输入的有效性。 始终假设您的用户将输入错误数据。 另请注意，我检查了我的 double 是否与零相等。 检查浮点相等性通常是一个坏主意，但在这里做是正确的。

然后，作为伪代码，我会写的是：

 // Get the operation (one of add/subtract/multiply or divide) - or allow the user to quit
 // Get each of value1 and value2 as doubles
 // Based on the operation, calculate the result (pay attention to division by zero)
 // Show the result
 // Loop back and let the user try again (or quit)

Answer 2

伪代码基本上就是在注释中写出你想要做的事情。 你的教授可能想教你的是做一堆注释来规划你的代码结构，然后编写你的代码。 你上面的已经是功能代码。 冒着回答你的作业问题的风险，我会说它是这样的：

switch(option)
{
    case 1:
        //do something
        break;
    case 2:
        //do something else
        break;
    default:
        //what to do if none of the cases are met
        break;
} 

Answer 3

我不知道你用伪代码是什么意思，但这段代码不那么重复：

double result = 0;
Console.Write("Enter First Number: ");
double num1 = Convert.ToDouble(Console.ReadLine());

Console.Write("Enter Second Number: ");
double num2 = Convert.ToDouble(Console.ReadLine());

Console.WriteLine("Enter a number from 1 to 3");
string input = Console.ReadLine();

switch (input) {

    case "1" : 
        result = num1 + num2;
        break;
    case "2":
        result = num1 - num2;
        break;
    case "3":
        result = num1 * num2;
        break;  
    default:
    Console.WriteLine("\n Next time follow instructions. You can only choose numbers 1 - 4");
    break;

}
Console.WriteLine("Result = " + result);