c# - 在 switch-case 条件中编写 switch-case 条件的可能性？

Question

我有这段代码，它按预期的方式运行。但是，如果用户在插入第一个值后单击 1、2 或 3，我想执行一些额外的操作。如您所见，如果用户第二次按 2，将显示按名字排列的玩家列表(至少这是我的意图)。所以我的问题是，这是否可以通过在前一个中插入一个 switch-case 条件来完成？我尝试过这样的事情:请参阅下面的更多代码。

 var isValidMenuItem = false;

        while (!isValidMenuItem)
            isValidMenuItem = Menu();

        Console.WriteLine();
        Console.ReadKey(true);

    }

    private static bool Menu()
    {
        Console.WriteLine("You have now entered the 2017 Wimbledon tournament!" + "\n" + "\n");
        Console.Write("Choose one of the 6 options:" + "\n" + "Press 1 for Default tournament:" + "\n" + "Press 2 for Women's single:" + "\n" +
            "Press 3 for Men's single:" + "\n" + "Press 4 for Women's double:" + "\n" + "Press 5 for Men's double:" + "\n" +
            "Press 6 for Mix double:" + "\n" + "Insert your choice...: ");

        var userValue = Console.ReadKey().KeyChar;
        Console.WriteLine();

        switch (userValue)
        {
            case '1':
                Console.WriteLine("\n"+ "You have entered a default tournament");
                break;
            case '2':
                Console.WriteLine("\n" + "You have entered women's single");
                Console.Write("Press 1 to start the tournament:" + "\n" + "Press 2 to list the players by first name:" + "\n" + 
                    "Press 3 to list the players by last name:" + "\n" + "Insert your choice...: ");
                break;
            case '3':
                Console.WriteLine("\n" + "You have entered men's single");
                Console.Write("Press 1 to start the tournament:" + "\n" + "Press 2 to list the players by first name:" + "\n" +
                    "Press 3 to list the players by last name:" + "\n" + "Insert your choice...: ");
                break;
            case '4':
                Console.WriteLine("\n" + "You have entered women's double");
                Console.Write("Press 1 to start the tournament:" + "\n" + "Press 2 to list the players by first name:" + "\n" +
                    "Press 3 to list the players by last name:" + "\n" + "Insert your choice...: ");
                break;
            case '5':
                Console.WriteLine("\n" + "You have entered men's double");
                Console.Write("Press 1 to start the tournament:" + "\n" + "Press 2 to list the players by first name:" + "\n" +
                    "Press 3 to list the players by last name:" + "\n" + "Insert your choice...: ");
                break;
            case '6':
                Console.WriteLine("\n" + "You have entered mix double");
                Console.Write("Press 1 to start the tournament:" + "\n" + "Press 2 to list the players by first name:" + "\n" +
                    "Press 3 to list the players by last name:" + "\n" + "Insert your choice...: ");
                break;
            default:
                Console.WriteLine("\n" + "Sorry! You have to choose one of the 6 tournament options");
                return false;
        }

像这样:……但是好像不行？你们有什么想法吗？

         case '2':
                Console.WriteLine("\n" + "You have entered women's single");
                Console.Write("Press 1 to start the tournament:" + "\n" + "Press 2 to list the players by first name:" + "\n" + 
                    "Press 3 to list the players by last name:" + "\n" + "Insert your choice...: ");
                {
                    switch (userValue)
                    {
                        case '1':
                            Console.WriteLine("Hello");
                            break;
                    }
                    break;
                }

Answer 1

switch 语句本身应该没问题。

问题出在变量 userValue 中。您只评估 var userValue = Console.ReadKey().KeyChar; 一次，因此该值被设置为那个键值。

例如，在您的示例中，外部 switch 语句输入 case '2'，因为这是 userValue 设置的内容。但是随后，当进入内部 switch 语句时，它再次使用相同的值，因为 ReadKey() 函数不再被计算。因此，您的 switch 语句会将“userValue”视为 2，甚至根本不会期望或等待任何输入，因此它会从 switch 中掉出来。

在这里编辑:您可以再次调用 ReadKey() 函数来解决这个问题，或者使用第二个变量:

//Inner switch statement:
//{ (bracket is redundant)
    userValue = Console.ReadKey().KeyChar;
    switch (userValue)
    {
        // switch body here...
    }
//}