Question

static void Main()
{
  Console.WriteLine("Please Input the type of coffee you want! Your options are small, medium, or large!");

  double coffeeprice = 0;
  string coffeechoice = Console.ReadLine();

  switch (coffeechoice.ToUpper())
  {
    case "SMALL":
      coffeeprice += 2.00;
      break;
    case "MEDIUM":
      coffeeprice += 4.00;
      break;
    case "LARGE":
      coffeeprice += 6.00;
      break;

  }
  Console.WriteLine("Generating receipt for your {0} order now!", coffeechoice);
 }
}

是的我知道代码编写不好等等。我知道有更好的方法可以做到这一点，但我确实是一个堕落的初学者。所有我想知道的是，如果我放置一个无效的语句，如果我放置HJFRJKLHRKLKEJS而不是小，中或大，我会在何处以及如何将while循环或while循环放入此语句中以使我回到开头。

Answer 1

Whelp我找到了答案！

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Please Input the type of coffee you want! Your options are small, medium, or large!");

        double coffeeprice = 0;

        string coffeechoice = Console.ReadLine();
        do
        {
            switch (coffeechoice.ToUpper())
            {
                case "SMALL":
                    coffeeprice += 2.00;
                    break;
                case "MEDIUM":
                    coffeeprice += 4.00;
                    break;
                case "LARGE":
                    coffeeprice += 6.00;
                    break;
                default:
                    Console.WriteLine("Invalid input please try again!");
                    coffeechoice = Console.ReadLine();
                    break;

            }
        } while (coffeechoice.ToUpper() != "SMALL" && coffeechoice.ToUpper() != "MEDIUM" && coffeechoice.ToUpper() != "LARGE");




        Console.WriteLine("Generating receipt for your {0} order now!", coffeechoice);
    }

}

原来我要做的就是将coffeechoice声明为Console.ReadLine（）;再次，所以它可能脱离背景存在！

Answer 2

你已经回答了自己的问题，但这是另一种方式。您已经注意到需要修复变量范围。这是你的另一个终止条件。我从零开始使用匹配价格，只在收到有效输入时设定价格。

//initialize coffeechoice to have it in scope at the end when you need it after the loop
string coffeechoice = "";
double coffeeprice = 0;

do {
    Console.WriteLine("Please Input the type of coffee you want! Your options are small, medium, or large!");
    coffeechoice = Console.ReadLine();
    switch (coffeechoice.ToUpper()) {
        case "SMALL":
            coffeeprice = 2.00;
            break;
        case "MEDIUM":
            coffeeprice = 4.00;
            break;
        case "LARGE":
            coffeeprice = 6.00;
            break;
    }
} while (coffeeprice == 0); //price not set, no valid input accepted

Console.WriteLine("Generating receipt for your {0} order now!", coffeechoice);
Console.WriteLine("You paid {0}", coffeeprice);

将它放在main方法中并尝试一下！

Answer 3

我认为你不需要在这里看一下：你可以定义一个案例＆＃34;默认＆＃34;如果输入不是这3个案例中的任何一个，请再次请求输入。要定义默认大小写，您可以执行以下操作：

default:
    Console.WriteLine("Please Input the type of coffee you want! Your options are small, medium, or               large!");    
string coffeechoice = Console.ReadLine();
    break;

Answer 4

您可以使用一个变量来指示输入是否有效（如下所示）。虽然可以检查coffeeprice == 0，但我不喜欢这种方法，因为它没有明确的输入，定价的变化也可能需要更改这个逻辑。

另外，我不确定为什么你只想在输入无效的情况下循环，因为这会使coffeeprice + =不必要。

bool isInputValid = false;
double coffeeprice = 0;
do
{
    Console.WriteLine("Please Input the type of coffee you want! Your options are small, medium, or large!");

    string coffeechoice = Console.ReadLine();
    isInputValid = true;
    switch (coffeechoice.ToUpper())
    {
        case "SMALL":
            coffeeprice += 2.00;
            break;
        case "MEDIUM":
            coffeeprice += 4.00;
            break;
        case "LARGE":
            coffeeprice += 6.00;
            break;
        default:
            isInputValid = false;
            break;
    }
}while (isInputValid == false);

Console.WriteLine("Generating receipt for your {0} order now!", coffeechoice);

Answer 5

您的代码就像这样

<强>更新：

double coffeprice=0;
do
{
Console.WriteLine("Enter you choice:");
string coffeechoice = Console.ReadLine();
switch (coffeechoice.ToUpper())
    {
        case "SMALL":
            coffeeprice += 2.00;
            break;
        case "MEDIUM":
            coffeeprice += 4.00;
            break;
        case "LARGE":
            coffeeprice += 6.00;
            break;

    }
}
while(coffeprice>0);

如何在这种情况下为C＃使用do while循环？

5 个答案: