C# 按 Enter 键时出错 - 程序崩溃

Question

我愚蠢地关闭了一个我认为最近已得到解答的问题，但我遇到了另一个问题。

在没有输入字符的情况下按下 Enter 键时，我的代码崩溃了。有办法防止这种情况吗？如果用户输入错误字符，则错误消息有效，但如果在没有放置任何输入的情况下按下 Enter 键，则会崩溃。

我收到的错误消息是在 mscorlib.dll 中发生了“System.FormatException”类型的未处理异常附加信息:字符串必须恰好是一个字符长。

这是我的代码:

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


namespace computerPackage
{
    class Program

    {
        static void Main(string[] args)
        {
            char computerPackage;
            const decimal DELUXE_PACKAGE = 1500;
            const decimal SUPER_PACKAGE = 1700;
            Console.Write("Input the Computer Package D or S: ");
            computerPackage = Char.Parse(Console.ReadLine());
            computerPackage = Char.ToUpper(computerPackage);
            if (computerPackage == 'D')
            {
                Console.WriteLine("Cost of Deluxe Computer Package is " + DELUXE_PACKAGE.ToString("C"));
            }
            else if (computerPackage == 'S')
            {
                Console.WriteLine("Cost of Deluxe Computer Package is " +
                SUPER_PACKAGE.ToString("C"));
            }
            else
            {
                Console.WriteLine("Package D or S not entered");
            }
            Console.WriteLine("Press any key to continue...");
            Console.ReadKey();          // pause
        }
    }
}

Answer 1

在您按下不带任何字符的回车键后，您的程序会尝试解析一个空字符串，这是不可能的，并且会给出异常。像这样在解析之前创建检查

    static void Main(string[] args)
    {
        char computerPackage;
        const decimal DELUXE_PACKAGE = 1500;
        const decimal SUPER_PACKAGE = 1700;
        Console.Write("Input the Computer Package D or S: ");
        string inp = Console.ReadLine();
        if (inp.Length==1)
        {
            computerPackage = Char.Parse(inp);
            computerPackage = Char.ToUpper(computerPackage);
            if (computerPackage == 'D')
            {
                Console.WriteLine("Cost of Deluxe Computer Package is " + DELUXE_PACKAGE.ToString("C"));
            }
            else if (computerPackage == 'S')
            {
                Console.WriteLine("Cost of Deluxe Computer Package is " +
                SUPER_PACKAGE.ToString("C"));
            }
            else
            {
                Console.WriteLine("Package D or S not entered");
            }
            Console.WriteLine("Press any key to continue...");
            Console.ReadKey();
        }
        else
            {
                Console.WriteLine("Package D or S not entered");
            }
            Console.WriteLine("Press any key to continue...");
            Console.ReadKey();

    }