我有这个代码以它应该的方式运行。但是，如果用户在插入第一个值后单击1,2或3，我希望实现额外的功能。正如您所看到的，如果用户第二次按下2，将显示名字的玩家列表（至少这是我的意图）。所以我的问题是，如果可以通过在前一个中插入switch-case条件来完成此操作？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：......但它似乎不起作用？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;
}
答案 0 :(得分：1)
switch语句本身应该没问题。
问题在于变量userValue。您只评估var userValue = Console.ReadKey().KeyChar;一次，因此该值设置为该一个键值。
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，当输入内部switch语句时，它使用相同的值AGAIN，因为ReadKey（）函数不会再次计算。 那么你的switch语句会将“userValue”视为2，甚至根本没有期待或等待任何输入，所以它就会掉出开关。
在这里编辑： 你可以再次调用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...
}
//}
答案 1 :(得分：0)
您的代码中有两件事
第一
如果您的开关值与代码中的开关值相同，则无法工作，因为一个变量只能有一个值。
第二
删除括号
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...: ");
//{ <- remove
switch (userValue)
{
case '1':
Console.WriteLine("Hello");
break;
}
break;
//} <- remove
答案 2 :(得分：0)
在我看来，那里有一个额外的花括号？不是吗？不应该是：
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;
default
return false;
}
break;
答案 3 :(得分：0)
您需要先重新读取该值。
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...: ");
userValue = Console.ReadKey().KeyChar;
{
switch (userValue)
{
case '1':
Console.WriteLine("Hello");
break;
}
}
break;
答案 4 :(得分：0)
除了损害可读性之外，将switch嵌套在另一个switch内也没问题。该语言完全支持它。
在你的情况下你的switch不起作用，因为你打开一个自进入外部开关后没有改变的变量，所以这个结构实际上没用。在输入嵌套开关之前添加代码以修改userValue，如下所示：
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...: ");
var userChoice = Console.ReadKey().KeyChar; // <<<<<==== Add this line
switch (userChoice) {
case '1':
Console.WriteLine("Hello");
break;
}
break;
答案 5 :(得分：0)
切换开关应该可以正常工作！
int x = 1;
switch(x)
{
case 1: // Enters Here cause x = 1
Console.WriteLine("test"); //prints
switch(x) // x still = 1
{
case 1: //enters here cause x = 1
Console.WriteLine("works"); //prints
break;
}
break;
default:
Console.WriteLine("doesnt work");
break;
}
（输出将是：＆＃34;测试＆＃34;＆＃34;工作＆＃34;）
你恰好写得很奇怪＆＃34; {}＆＃34;，那是问题吗？
如果要输入不同的Switch案例，则必须更改开关（值）的值以输入不同的情况。
在你的情况下：
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...: ");
//Ask for a new input here = (NEWVALUE)
switch (NEWVALUE)
{
case '1':
Console.WriteLine("Hello");
break;
}
break;
答案 6 :(得分：0)
首先，您不需要嵌套开关。你必须连续选择两件事：
因此，您可以为锦标赛类型创建枚举：
public enum TournamentType
{
Default,
SingleWomen,
SingleMen,
DoubleWomen,
DoubleMen,
DoubleMix
}
然后你需要选择选项。您可以在此处使用switch语句，但您也可以创建选项选择器类：
public class OptionSelector<T>
{
private readonly List<Option> options = new List<Option>();
public T SelectedOption { get; private set; }
public OptionSelector<T> WithOption(T value, string title)
{
options.Add(new Option { Value = value, Title = title });
return this;
}
public bool SelectOption()
{
if (!options.Any()) return true;
Console.WriteLine($"Choose one of the {options.Count} options:");
for(int i = 0; i < options.Count; i++)
Console.WriteLine($" {i + 1} - {options[i].Title}");
Console.Write("Your choice: ");
var key = Console.ReadKey().KeyChar;
Console.WriteLine();
int choice = key - '0';
if (!Char.IsDigit(key) || choice == 0 || options.Count < choice) {
Console.WriteLine($"Sorry, only digits 1..{options.Count} are allowed");
return false;
}
SelectedOption = options[choice - 1].Value;
return true;
}
private class Option {
public T Value { get; set; }
public string Title { get; set; }
}
}
几行代码，但功能很好 - 这个类允许以流畅的方式构建一组选项，然后接受用户输入。如果输入有效，则可通过SelectedOption属性使用所选选项。否则将显示详细的错误消息。这里的好处是选项选择器是一个通用类。每个选项都可以是字面上的任何东西 - 整数，字符串，枚举值，甚至是方法。使用此类，您的所有代码都可以折叠为：
Console.WriteLine($"You have now entered the 2017 Wimbledon tournament!\n");
var tournamentTypeSelector = new OptionSelector<TournamentType>()
.WithOption(TournamentType.Default, "Default tournament")
.WithOption(TournamentType.SingleWomen, "Women's single")
.WithOption(TournamentType.SingleMen, "Men's single")
.WithOption(TournamentType.DoubleWomen, "Women's double")
.WithOption(TournamentType.DoubleMix, "Mix double");
while (!tournamentTypeSelector.SelectOption()) { /*Console.Clear();*/ }
var tournamentType = tournamentTypeSelector.SelectedOption;
var actionSelector = new OptionSelector<Action>()
.WithOption(() => StartTournament(tournamentType), "Start the tournament")
.WithOption(() => Console.WriteLine("Not implemented"), "List players by first name")
.WithOption(() => Console.WriteLine("Not implemented"), "List players by last name");
while (!actionSelector.SelectOption()) { /*Console.Clear();*/ }
actionSelector.SelectedOption(); // invoke selected action
宇呼！根本没有开关
此处的第一个选择器选择锦标赛类型。第二个选择器选择要调用的动作。这里的好处是你可以将参数传递给那些动作（例如锦标赛类型）。 Btw StartTournament是包含相应功能的方法：
private static void StartTournament(TournamentType tournamentType)
{
// your code here
Console.WriteLine("Tournament started");
}
检查Fiddle以查看其工作原理。请注意，小提琴不支持Console.ReadKey，因此您应该每次都按Enter键。