Question

我正在尝试为C＃.NET控制台应用程序编写一个简单的箭头驱动选项菜单。给定字符返回类型的选项字典，用户可以选择带有向上/向下键的选项，并使用回车键选择它。

问题是，switch语句在第一次运行后完全中断了程序。我试过放置断点并搞清楚，但无济于事 -

编辑：决定将此代码与某些异步代码分开那也被写入了班级。无论出于何种原因，这都可以它按预期工作，所以..现在我需要找出为什么异步会搞乱这个，没有等待像这样的同步操作这个..

代码：

    static char GetUserInput(Dictionary<char, String> options, int indent = 1) {

        int optionAreaTop = Console.CursorTop;
        Console.ForegroundColor = ConsoleColor.Yellow;

        // First option, makes sure it's set in yellow
        bool fo = true;

        foreach (String opt in options.Values) {
            Console.WriteLine(opt.PadLeft(indent + opt.Length, '\t'));
            if (fo) { Console.ForegroundColor = ConsoleColor.White; fo = false; }
        }


        return DoMenu(options, optionAreaTop);

    }

    static char DoMenu(Dictionary<char, String> options, int optionAreaTop = 0) {
        int answerIndex = 0;
        int currentAnswerTop = optionAreaTop;
        int indent = 2;
        while (true) {

            ConsoleKeyInfo kin = Console.ReadKey(true);
            ConsoleKey ki = kin.Key;

            switch (ki) {
                case ConsoleKey.UpArrow:
                    if (currentAnswerTop - 1 >= optionAreaTop) {
                        // Rewrite selection in white
                        WriteOptionLine(currentAnswerTop, indent, options.Values.ElementAt(answerIndex), ConsoleColor.White);
                        WriteOptionLine(currentAnswerTop - 1, indent, options.Values.ElementAt(answerIndex - 1), ConsoleColor.Yellow);
                        currentAnswerTop -= 1;
                        answerIndex -= 1;
                    }
                    break;

                case ConsoleKey.DownArrow:
                    if (answerIndex + 1 < options.Count - 1) {
                        // Rewrite selection in white
                        WriteOptionLine(currentAnswerTop, indent, options.Values.ElementAt(answerIndex), ConsoleColor.White);
                        WriteOptionLine(currentAnswerTop + 1, indent, options.Values.ElementAt(answerIndex + 1), ConsoleColor.Yellow);
                        currentAnswerTop += 1;
                        answerIndex += 1;
                    }

                    break;

                case ConsoleKey.Enter:
                    return options.Keys.ElementAt(answerIndex);

                default:
                    // Retry
                    break;
            }
        }
    }

    static void WriteOptionLine(int position, int indent, String option, ConsoleColor color) {
        Console.SetCursorPosition(0, position);
        Console.ForegroundColor = color;
        Console.WriteLine(option.PadLeft(indent + option.Length, '\t'));
    }

用法：

Dictionary<char, String> opts = new Dictionary<char, string>();
opts.Add('r', "[R]etry the Download");
opts.Add('m', "[M]anually add the file");
opts.Add('s', "[S]kip the file");

// GET_USER_INPUT
char choice = GetUserInput(opts, 2);

// DO WHATEVER

Answer 1

除了一个代码之外，你的代码没有问题，因为我在我的控制台应用程序中测试了它，因为if中的ArrowDown条件，所以永远不会选择最后一个选项，所以它会像：

 case ConsoleKey.DownArrow:
          if (answerIndex + 1 <= options.Count - 1)
          {
               // Rewrite selection in white
               WriteOptionLine(currentAnswerTop, indent, options.Values.ElementAt(answerIndex), ConsoleColor.White);
               WriteOptionLine(currentAnswerTop + 1, indent, options.Values.ElementAt(answerIndex + 1), ConsoleColor.Yellow);
               currentAnswerTop += 1;
               answerIndex += 1;
          }
          break;

if (answerIndex + 1 < options.Count - 1)应为if (answerIndex + 1 <= options.Count - 1)

很明显，按Enter键控制台应用程序将退出，因为您从DoMenu返回return options.Keys.ElementAt(answerIndex);并且choice变量将被选中。

C＃控制台菜单：单次运行后转义循环

1 个答案: