Question

以下是我正在处理的定义。但我无法继续前进。 Switch语句不起作用，直接显示默认的msg。有人可以帮我吗？

允许用户从三盒水果（苹果，香蕉或樱桃）中选择一种，然后询问水果盒的数量（5,10或15）。每个水果盒的成本如下：苹果 - 0.25美元，香蕉 - 1.60美元，樱桃 - 2.50美元。如果选择了有效的水果盒，则只应向用户请求水果盒的数量。否则显示错误消息并退出应用程序。选择水果类型和数量后，显示总价（水果盒价格乘以箱数量）。如果用户未选择有效数量，则将数量设置为零并显示错误消息。

更新代码

Console.Clear();
Console.WriteLine("\t Purchasing Fruit System\n");
Console.WriteLine("Select Fruit");
Console.WriteLine("A - Apples ");
Console.WriteLine("B - Bananas ");
Console.WriteLine("C - Cherries ");
Console.Write("Enter Your Selection: ");


string menuSelection = null;
double totalPrice = double.MinValue;
int numOfBoxes = int.MinValue;

//Get Fruit Selection
menuSelection = Console.ReadLine();

//Add a switch statement to set Price
switch (menuSelection.ToLower())
{
    case "a":
        totalPrice = 0.25;
        menuSelection = "Apples";
        break;
    case "b":
        totalPrice = 1.60;
        menuSelection = "Bananas";
        break;
    case "c":
        totalPrice = 2.50;
        menuSelection = "Cherries";
        break;
    default:
        Console.WriteLine("Invalid Selection !");
        Console.ReadLine();
        return;
} 
//Display Menu of Quantitites as Long as a Valid
Console.WriteLine();
Console.WriteLine("How many boxes of {0} do you want ?", menuSelection);
Console.WriteLine("1 - 5 {0}", menuSelection);
Console.WriteLine("2 - 10 {0}", menuSelection);
Console.WriteLine("3 - 15 {0}", menuSelection);
Console.Write("Enter your Selection: ");
//Get Quantity Selection
string value = Console.ReadLine();
if (!int.TryParse (value, out numOfBoxes) || numOfBoxes < 1 || numOfBoxes > 3)
{
    Console.WriteLine("Invalid Selection! Quantity is Zero");
    Console.WriteLine();
    return;
}
//Add a switch statement to set Quantity
switch (numOfBoxes)
{
    case 1:
        totalPrice *= 5;
        break;
    case 2:
        totalPrice *= 10;
        break;
    case 3:
        totalPrice *= 15;
        break;
}
//Display Total for Fruit
if (numOfBoxes <=3)
    Console.WriteLine("Quantity is zero Your total is $ 0.00");
else
    Console.WriteLine("Total price of {0} boxes of {1} is: {2}", numOfBoxes, menuSelection, totalPrice);

//Pause Display 
Console.WriteLine("Press Any Key to Continue.............");
Console.ReadKey();

Answer 1

您在switch声明中使用了不同的变量，我认为您需要menuSelection而不是switchSelection

switch(menuSelection)
{
   ...
}

Answer 2

根据您的代码风格，我可以提出下一个代码。

        Console.Clear();
        Console.WriteLine("\t Purchasing Fruit System\n");
        Console.WriteLine("Select Fruit");
        Console.WriteLine("A - Apples ");
        Console.WriteLine("B - Bananas ");
        Console.WriteLine("C - Cherries ");
        Console.Write("Enter Your Selection: ");


        string menuSelection = null;
        double totalPrice = double.MinValue;
        int numOfBoxes = int.MinValue;

        menuSelection = Console.ReadLine ();

        switch (menuSelection) {
        case "a":
        case "A":
            totalPrice = 0.25;
            menuSelection = "Apples";
            break;
        case "b":
        case "B":
            totalPrice = 1.60;
            menuSelection = "Bananas";
            break;
        case "c":
        case "C":
            totalPrice = 2.50;
            menuSelection = "Cherries";
            break;
        default:
            Console.WriteLine ("Invalid Selection !");
            return;
        }

        //Display Menu of Quantitites as Long as a Valid
        Console.WriteLine("How many boxes of {0} do you want ?", menuSelection);
        Console.WriteLine("1 - 5 {0}", menuSelection);
        Console.WriteLine("2 - 10 {0}", menuSelection);
        Console.WriteLine("3 - 15 {0}", menuSelection);
        Console.Write("Enter your Selection: ");

        //Get Quantity Selection
        string value = Console.ReadLine ();
        if (!int.TryParse (value, out numOfBoxes) || numOfBoxes < 1 || numOfBoxes > 3) {
            Console.WriteLine("Invalid Selection !");
            numOfBoxes = 0;
            }

        switch (numOfBoxes) {
        case 1:
            totalPrice *= 5;
            break;
        case 2:
            totalPrice *= 10;
            break;
        case 3:
            totalPrice *= 15;
            break;
        }

        if(numOfBoxes == 0)
            Console.WriteLine("Quantity is zero Your total is $ 0.00");
        else
            Console.WriteLine("Total price of {0} boxes of {1} is: {2}", numOfBoxes, menuSelection, totalPrice);

        Console.ReadLine();

切换语句错误，无法显示信息

2 个答案: