C# 控制台应用程序——尝试从 else 语句访问列表

Question

这是一个数据结构和算法类。我们刚刚开始使用冒泡排序。指令是生成随机的、唯一的整数，并使用讲座中的排序技术对它们进行排序。还需要添加不同的排序技术。

为了生成随机数列表，我生成了一个列表，然后使用 fisher-yates 算法对列表进行了混洗。因此，无论我选择什么大小，我都有自己独特的排序列表。

我卡住了，因为在生成随机列表后，我无法访问列表以通过 BubbleSort 运行它。

有什么办法可以做到这一点吗？

 class Algorithms
{
    static void Main(string[] args)
    {         

        string response = "";

        //Main Console Menu
        while (response != "exit") 
        {
            Console.WriteLine("Type help for list of commands");
            response = Console.ReadLine();
           //List<int> toSort = new List<int>();

            if (response.StartsWith("exit"))
            {
                Environment.Exit(0);
            }

            else if (response.ToLower().StartsWith("help"))
            {
                Help(response);
            }

            else if (response.ToLower().StartsWith("generate"))
            {

            // Shuffle(Generate(response));
            // have been using the line above but adding next line for
            //an idea of my problem

            List<int> toSort = Shuffle(Generate(response));

            }

            else if (response.ToLower().StartsWith("bubble"))
            {
                //This doesn't work and I'm trying to figure out how it can
                BubbleSort(toSort); 

            }                           

        }
    }


    //Displays help information 
    public static void Help(string input)
        {
        Console.WriteLine("\ngenerate <integer>   --  Generates a data set of intended amount of integers\n"+
            "algorithm <algorithm type>  -- Choose which algorithm to sort data\nexit   --   exit application\n" ); 
        }

    //Generates List of integers from 0 to number choosen by user
    public static List<int> Generate(string size)
    {
        int cutString = size.Length - 9; 
        string sizeSubset = size.Substring(9, cutString);            
        List<int> numGen = new List<int>();
        int dataSetSize = Convert.ToInt32(sizeSubset); 
        for(int i = 0; i <= dataSetSize; i++)
        {
            numGen.Add(i);
          // Console.WriteLine(numGen[i]);                

        }

        return numGen;                  

    }

    //Use Fisher-Yates algorithm to shuffle the list. 
    static Random randomize = new Random();
    public static List<int> Shuffle(List<int>makeRandom)
    {

        List<int> shuffled = new List<int>();
        int n = makeRandom.Count;
        while (n > 1)
        {
            n--;
            int k = randomize.Next(n + 1);
            int value = makeRandom[k];
            makeRandom[k] = makeRandom[n];
            makeRandom[n] = value;
            shuffled.Add(value);
            Console.WriteLine(value);

        }

        return shuffled;

    }

    public static void BubbleSort(List<int>input)
    {
        for(int i = 0; i <= input.Count; i++)
        {
            for (int j = 0; j <= (input.Count - 1); j++)
            {
                if (input[j] > input[j + 1])
                {
                    int temp = input[j];
                    input[j] = input[j + 1];
                    input[j + 1] = temp;
                    Console.WriteLine("hello");
                }

            }
        }
    }

}
}

Answer 1

您在 else if (response.ToLower().StartsWith("generate")) 代码块的范围内定义了列表，因此无法在该 block 之外访问它。将声明移动到 Main 方法范围，如下所示:

static void Main(string[] args)
{         

    string response = "";
    //define your list here.
    List<int> toSort = new List<int>();

    //Main Console Menu
    while (response != "exit") 
    {
        Console.WriteLine("Type help for list of commands");
        response = Console.ReadLine();

        if (response.StartsWith("exit"))
        {
            Environment.Exit(0);
        }

        else if (response.ToLower().StartsWith("help"))
        {
            Help(response);
        }

        else if (response.ToLower().StartsWith("generate"))
        {
            toSort = Shuffle(Generate(response));
        }

        else if (response.ToLower().StartsWith("bubble"))
        {

            List<int> sortedList = BubbleSort(toSort); 
        }                           

    }
}