Question

我正在尝试创建一个程序，一次从文本文件中读取一个项目，直到它读取所有项目。每次它向屏幕读取项目时，用户输入1,2或3.根据输入的内容，读取的项目将添加到相应的ArrayList。完成后，它会打印出三个数组中的所有项目。这对我来说不起作用，似乎总是进入默认的switch语句，在我第一次输入数字之后，它会读出3个而不是1个项目。是的，它很乱，我正在寻找一些方向，但期待更多的学习基本的第一个孩子的反应。

以下是代码：

class SplitCheck
{
    IList byte mylist = new IList   

    static void Main(string[] args)
    {
        byte guestlist;
        ArrayList Guest1 = new ArrayList();
        ArrayList Guest2 = new ArrayList();
        ArrayList Guest3 = new ArrayList();

        Console.WriteLine("Thank you for dining with us.");

        // Create a path to the My Documents folder and the file name
        string filePath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) +
                                    Path.DirectorySeparatorChar + "Food.txt";

        // Read the contents of the file using ReadAllLines
        Console.WriteLine("Please assign each item a guest number");
        string[] contents = File.ReadAllLines(filePath);
        foreach (string s in contents)
        {
            Console.WriteLine(s);
            guestlist = (byte)Console.Read();


            switch (guestlist)
            {
                case 1 :
                    //Add to a guest1 array
                    Guest1.Add(s);
                    Console.WriteLine("{0} has been added to Guest1", s);
                    break;
                case 2:
                    //Add to a guest2 array
                    Guest2.Add(s);
                    Console.WriteLine("{0} has been added to Guest2", s);
                    break;
                case 3:
                    //Add to a guest3 array
                    Guest3.Add(s);
                    Console.WriteLine("{0} has been added to Guest3", s);
                    break;
                default:
                    //Add to default array
                    Console.WriteLine("Default has been used");
                    break;



            }
        }

        foreach (object o in Guest1)
        {
            Console.WriteLine("Guest 1 had {0}", o);
        }

        foreach (object o in Guest2)
        {
            Console.WriteLine("Guest 2 had {0}", o);
        }

        foreach (object o in Guest3)
        {
            Console.WriteLine("Guest 3 had {0}", o);
        }

        Console.ReadLine();
        //Console.WriteLine("Guest 2 had {0}", Guest2());
        //Console.WriteLine("Guest 3 had {0}", Guest3());
        //Console.ReadLine();
    }
}

Answer 1

guestlist不应该是byte类型，你想要它的类型为char。试试看，如果你仍然坚持阅读：

提示＃2：输入1，然后在guestList的值上放置一个断点。有什么价值？它是49.这个数字有什么重要意义？提示：想想ASCII。

所以试试这个：

char guestlist;
ArrayList Guest1 = new ArrayList();
ArrayList Guest2 = new ArrayList();
ArrayList Guest3 = new ArrayList();

Console.WriteLine("Thank you for dining with us.");

// Create a path to the My Documents folder and the file name
string filePath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocum
                            Path.DirectorySeparatorChar + "Food.txt";

// Read the contents of the file using ReadAllLines
Console.WriteLine("Please assign each item a guest number");
string[] contents = File.ReadAllLines(filePath);
foreach (string s in contents)
{
    Console.WriteLine(s);
    guestlist = (char)Console.Read();

    switch (guestlist)
    {
        case '1':
            //Add to a guest1 array
            Guest1.Add(s);
            Console.WriteLine("{0} has been added to Guest1", s);
            break;
        case '2':
            //Add to a guest2 array
            Guest2.Add(s);
            Console.WriteLine("{0} has been added to Guest2", s);
            break;
        case '3':
            //Add to a guest3 array
            Guest3.Add(s);
            Console.WriteLine("{0} has been added to Guest3", s);
            break;
        default:
            //Add to default array
            Console.WriteLine("Default has been used");
            break;

Answer 2

您的问题在这里

guestlist = (byte)Console.Read();

将其更改为

guestlist = Convert.ToInt32(Console.ReadLine());

您正在将控制台读取数据作为一个字节进行转换，并根据反馈进行更新。

Answer 3

您可以直接检查Console.ReadKey的结果，而不是从Console.Read()解释整数值，只需更新字典而不需要switch语句：

var guestCounts = new Dictionary<int, List<string>>
{
    { 1, new List<string>() },
    { 2, new List<string>() },
    { 3, new List<string>() }
}

// Collect inputs
foreach (string food in File.ReadAllLines(filePath))
{
    int guest;
    if (int.TryParse(Console.ReadKey().KeyChar.ToString(), out guest) &&
        guestCounts.ContainsKey(guest))
    {
        guestCounts[guest].Add(food);
        Console.WriteLine("{0} has been added to Guest{1}", food, guest);
    }
    else
    {
        Console.WriteLine("Default has been used.");
    }
}

// Output results
foreach (int guest in guestCounts.Keys)
{
    foreach (string food in guestCounts[guest])
    {
        Console.WriteLine("Guest {0} had {1}", guest, food);
    }
}

Answer 4

读入的值是字符的ASCII表示形式，而不是实际字符。此外，当人按下ENTER键时，Console.Read方法也将在换行符中读取，这将导致循环三次（字符，然后是回车符和换行符）。

我建议使用int.TryParse检查输入是否有效，将输入转换为int类型，最后使用Console.ReadLine消除当人按ENTER时的换行符。

        int val;
        var success = int.TryParse(Console.ReadLine(), out val);

        if (success)
        {
            switch (val)
            {
                case 1:
                    Console.WriteLine("has been added to Guest1");
                    break;
                case 2:
                    Console.WriteLine("has been added to Guest2");
                    break;
                case 3:
                    Console.WriteLine("has been added to Guest3");
                    break;
                default:
                    Console.WriteLine("Default has been used");
                    break;
            }
        }
        else
        {
            Console.WriteLine("Invalid value");
        }

将用户输入存储到ArrayList中

4 个答案: