用户按错键后如何重新开始循环？答案

【问题标题】：How to start a loop over again after a user pressed a wrong key?用户按错键后如何重新开始循环？
【发布时间】：2013-12-21 16:37:48
【问题描述】：

所以我想做的是用 C# 创建一个简单的基于文本的 RPG 游戏。在询问玩家他/她想使用什么武器后，如果用户按下了无效的键，我希望能够重新开始循环。

//Runs battle interactive
Console.WriteLine("");
Console.WriteLine("You have encountered a simple guard!  He deals 2 damage per attack and has 1 HP.");
Console.WriteLine("You currently have: " + Program.Inventory);
Console.WriteLine("Choose a weapon!");
var input2 = Console.ReadKey();

//Key checker for items
switch (input2.Key)
{
    case ConsoleKey.D1:
        Console.WriteLine("");
        if (Items.iniFists == true)
        {
            Console.WriteLine("You have attacked with your Fists for 1 DMG!");
        }else
        {
            //this will never run, just a placeholder
            Console.WriteLine("You Don't have your fists!");
            switch (input2.Key)
{
    case ConsoleKey.D1:
        Console.WriteLine("");
        if (Items.iniFists == true)
        {
            Console.WriteLine("You have attacked with your Fists for 1 DMG!");
        }else
        {
            //this will never run, just a placeholder
            Console.WriteLine("You Don't have your fists!");
        }
        break;
    case ConsoleKey.D2:
        Console.WriteLine("");
        if (Items.iniLongsword == true)
        {
        Console.WriteLine("You have chosen to attack with the Longsword for 2 DMG!");
        }else
        {
            Console.WriteLine("You don't have a longsword!");
        }
        break;
    case ConsoleKey.D3:
        Console.WriteLine("");
        if (Items.iniBow == true)
        {
            Console.WriteLine("You have chosen to attack with the Bow for 3 DMG!");
        }
        else
        {
            Console.WriteLine("You don't have a Bow!");
        }
        break;
    case ConsoleKey.D4:
        Console.WriteLine("");
        if (Items.iniLightstaff == true)
        {
            Console.WriteLine("You have chosen to attack with the Lightstaff for 4 DMG!");
        }
        else
        {
            Console.WriteLine("You don't have a Lightstaff!");
        }
        break;
    case ConsoleKey.D5:
        Console.WriteLine("");
        Console.WriteLine("You can't attack with an Apple!");
        break;
    case ConsoleKey.D6:
        Console.WriteLine("");
        Console.WriteLine("You can't attack with a Golden Key!");
        break;
    case ConsoleKey.D7:
        Console.WriteLine("");
        Console.WriteLine("You can't attack with a Steak!");
        break;
}
        }
        break;
    case ConsoleKey.D2:
        Console.WriteLine("");
        if (Items.iniLongsword == true)
        {
        Console.WriteLine("You have chosen to attack with the Longsword for 2 DMG!");
        }else
        {
            Console.WriteLine("You don't have a longsword!");
        }
        break;
    case ConsoleKey.D3:
        Console.WriteLine("");
        if (Items.iniBow == true)
        {
            Console.WriteLine("You have chosen to attack with the Bow for 3 DMG!");
        }
        else
        {
            Console.WriteLine("You don't have a Bow!");
        }
        break;
    case ConsoleKey.D4:
        Console.WriteLine("");
        if (Items.iniLightstaff == true)
        {
            Console.WriteLine("You have chosen to attack with the Lightstaff for 4 DMG!");
        }
        else
        {
            Console.WriteLine("You don't have a Lightstaff!");
        }
        break;
    case ConsoleKey.D5:
        Console.WriteLine("");
        Console.WriteLine("You can't attack with an Apple!");
        break;
    case ConsoleKey.D6:
        Console.WriteLine("");
        Console.WriteLine("You can't attack with a Golden Key!");
        break;
    case ConsoleKey.D7:
        Console.WriteLine("");
        Console.WriteLine("You can't attack with a Steak!");
        break;
}

例如，如果玩家按下 7 键，游戏会告诉他们不能用牛排进行攻击。告诉玩家之后，如何让玩家选择其他物品？

【问题讨论】：

在我看来，你发布的代码太多了。
@AgentMcBride：你可以使用 wile(true) 循环，看我的回答。
@AgentMcBride 将您的 UI 功能与您的程序的功能混合往往会使您的代码更难维护。一旦您的代码正常工作，我建议您向 codereview.stackexchange.com 询问有关使其更清洁和更易于维护的建议。

标签： c# loops key

【解决方案1】：

这是你的代码包裹在一个循环中：

bool correct = false;
do
{
    Console.WriteLine("");
    Console.WriteLine("You have encountered a simple guard!  He deals 2 damage per attack and has 1 HP.");
    Console.WriteLine("You currently have: " + Program.Inventory);
    Console.WriteLine("Choose a weapon!");
    var input2 = Console.ReadKey();

    correct = true;
    //Key checker for items
    switch (input2.Key)
    {
        case ConsoleKey.D1:
            Console.WriteLine("");
            if (Items.iniFists == true)
            {
                Console.WriteLine("You have attacked with your Fists for 1 DMG!");
            }
            else
            {
                //this will never run, just a placeholder
                Console.WriteLine("You Don't have your fists!");
                switch (input2.Key)
                {
                    case ConsoleKey.D1:
                        Console.WriteLine("");
                        if (Items.iniFists == true)
                        {
                            Console.WriteLine("You have attacked with your Fists for 1 DMG!");
                        }
                        else
                        {
                            //this will never run, just a placeholder
                            Console.WriteLine("You Don't have your fists!");
                        }
                        break;
                    case ConsoleKey.D2:
                        Console.WriteLine("");
                        if (Items.iniLongsword == true)
                        {
                            Console.WriteLine("You have chosen to attack with the Longsword for 2 DMG!");
                        }
                        else
                        {
                            Console.WriteLine("You don't have a longsword!");
                        }
                        break;
                    case ConsoleKey.D3:
                        Console.WriteLine("");
                        if (Items.iniBow == true)
                        {
                            Console.WriteLine("You have chosen to attack with the Bow for 3 DMG!");
                        }
                        else
                        {
                            Console.WriteLine("You don't have a Bow!");
                        }
                        break;
                    case ConsoleKey.D4:
                        Console.WriteLine("");
                        if (Items.iniLightstaff == true)
                        {
                            Console.WriteLine("You have chosen to attack with the Lightstaff for 4 DMG!");
                        }
                        else
                        {
                            Console.WriteLine("You don't have a Lightstaff!");
                        }
                        break;
                    case ConsoleKey.D5:
                        Console.WriteLine("");
                        Console.WriteLine("You can't attack with an Apple!");
                        break;
                    case ConsoleKey.D6:
                        Console.WriteLine("");
                        Console.WriteLine("You can't attack with a Golden Key!");
                        break;
                    case ConsoleKey.D7:
                        Console.WriteLine("");
                        Console.WriteLine("You can't attack with a Steak!");
                        break;
                }
            }
            break;
        case ConsoleKey.D2:
            Console.WriteLine("");
            if (Items.iniLongsword == true)
            {
                Console.WriteLine("You have chosen to attack with the Longsword for 2 DMG!");
            }
            else
            {
                Console.WriteLine("You don't have a longsword!");
            }
            break;
        case ConsoleKey.D3:
            Console.WriteLine("");
            if (Items.iniBow == true)
            {
                Console.WriteLine("You have chosen to attack with the Bow for 3 DMG!");
            }
            else
            {
                Console.WriteLine("You don't have a Bow!");
            }
            break;
        case ConsoleKey.D4:
            Console.WriteLine("");
            if (Items.iniLightstaff == true)
            {
                Console.WriteLine("You have chosen to attack with the Lightstaff for 4 DMG!");
            }
            else
            {
                Console.WriteLine("You don't have a Lightstaff!");
            }
            break;
        case ConsoleKey.D5:
            Console.WriteLine("");
            Console.WriteLine("You can't attack with an Apple!");
            break;
        case ConsoleKey.D6:
            Console.WriteLine("");
            Console.WriteLine("You can't attack with a Golden Key!");
            break;
        case ConsoleKey.D7:
            Console.WriteLine("");
            Console.WriteLine("You can't attack with a Steak!");
            break;
        default:
            correct = false;
            break;
    }
}
while (!correct);

【讨论】：

对不起，我对编程有点陌生，这到底在哪里？
@AgentMcBride 将该循环包裹在您的 switch 语句周围。
@sysexpand 所以在我把它放在我的代码中之后，它只会说当我输入错误的数字时选择武器，没有别的。
在默认部分添加您认为适合错误键的任何代码，例如打印出消息。循环将允许用户再次选择。

【解决方案2】：

示例代码：

string key;
do {

   key = Console.Read(); 
   if(key == ..) {
   }
   else if(key == ...) {
   }
   else if(..) {
   }

}while(key == WRONG_KEY);

【讨论】：

【解决方案3】：

您需要打印出“请按另一个键”，然后添加一个新的输入变量和 switch 语句。这样用户可以按两次键7。当用户第一次按下按钮时，第一个开关将用于做任何你想做的事情。第二个 switch 语句将控制用户再次按键时发生的情况。

           var input2 = Console.ReadKey();

            //Key checker for items
            switch (input2.Key)
            {
               //CODE HERE (PRINT PLEASE PRESS ANOTHER KEY)
            }

           var input3 = Console.ReadKey();
            switch (input3.Key)
            {
               //CODE HERE 
            }

【讨论】：

【解决方案4】：

您可以使用while(true)解决问题。

如果您使用while(true)，它将迭代infinite 次，但如果一旦用户输入无效输入，您应该确保quit 循环。

如果用户输入了无效的输入然后没有 switch case mathces，那么它进入default 块，在默认块中你可以使用return 语句退出循环。

示例代码：

    Console.WriteLine("Please enter key 1-5");
    int key =Convert.Int32(Console.ReadLine());

    while (true)
    {
        switch (key)
        {
            case 1: Console.WriteLine("ur option "+key);
                break;
            case 2: Console.WriteLine("ur option " + key);
                break;
            case 3: Console.WriteLine("ur option " + key);
                break;
            case 4: Console.WriteLine("ur option " + key);
                break;
            case 5: Console.WriteLine("ur option " + key);
                break;
            default:
                Console.WriteLine("invalid choice ,quitting the loop");
                return;

        }
        Console.WriteLine("Please enter key 1-5");
         key = Console.ReadLine();
    }
    Console.WriteLine("outside loop");

完整代码：

            Console.WriteLine("");
            Console.WriteLine("You have encountered a simple guard!  He deals 2 damage per attack and has 1 HP.");
            Console.WriteLine("You currently have: " + Program.Inventory);
            Console.WriteLine("Choose a weapon!");
            var input2 = Console.ReadKey();

            //Key checker for items
            while(true)
            {
            switch (input2.Key)
            {
                case ConsoleKey.D1:
                    Console.WriteLine("");
                    if (Items.iniFists == true)
                    {
                        Console.WriteLine("You have attacked with your Fists for 1 DMG!");
                    }else
                    {
                        //this will never run, just a placeholder
                        Console.WriteLine("You Don't have your fists!");
                        switch (input2.Key)
            {
                case ConsoleKey.D1:
                    Console.WriteLine("");
                    if (Items.iniFists == true)
                    {
                        Console.WriteLine("You have attacked with your Fists for 1 DMG!");
                    }else
                    {
                        //this will never run, just a placeholder
                        Console.WriteLine("You Don't have your fists!");
                    }
                    break;
                case ConsoleKey.D2:
                    Console.WriteLine("");
                    if (Items.iniLongsword == true)
                    {
                    Console.WriteLine("You have chosen to attack with the Longsword for 2 DMG!");
                    }else
                    {
                        Console.WriteLine("You don't have a longsword!");
                    }
                    break;
                case ConsoleKey.D3:
                    Console.WriteLine("");
                    if (Items.iniBow == true)
                    {
                        Console.WriteLine("You have chosen to attack with the Bow for 3 DMG!");
                    }
                    else
                    {
                        Console.WriteLine("You don't have a Bow!");
                    }
                    break;
                case ConsoleKey.D4:
                    Console.WriteLine("");
                    if (Items.iniLightstaff == true)
                    {
                        Console.WriteLine("You have chosen to attack with the Lightstaff for 4 DMG!");
                    }
                    else
                    {
                        Console.WriteLine("You don't have a Lightstaff!");
                    }
                    break;
                case ConsoleKey.D5:
                    Console.WriteLine("");
                    Console.WriteLine("You can't attack with an Apple!");
                    break;
                case ConsoleKey.D6:
                    Console.WriteLine("");
                    Console.WriteLine("You can't attack with a Golden Key!");
                    break;
                case ConsoleKey.D7:
                    Console.WriteLine("");
                    Console.WriteLine("You can't attack with a Steak!");
                    break;
            }
                    }
                    break;
                case ConsoleKey.D2:
                    Console.WriteLine("");
                    if (Items.iniLongsword == true)
                    {
                    Console.WriteLine("You have chosen to attack with the Longsword for 2 DMG!");
                    }else
                    {
                        Console.WriteLine("You don't have a longsword!");
                    }
                    break;
                case ConsoleKey.D3:
                    Console.WriteLine("");
                    if (Items.iniBow == true)
                    {
                        Console.WriteLine("You have chosen to attack with the Bow for 3 DMG!");
                    }
                    else
                    {
                        Console.WriteLine("You don't have a Bow!");
                    }
                    break;
                case ConsoleKey.D4:
                    Console.WriteLine("");
                    if (Items.iniLightstaff == true)
                    {
                        Console.WriteLine("You have chosen to attack with the Lightstaff for 4 DMG!");
                    }
                    else
                    {
                        Console.WriteLine("You don't have a Lightstaff!");
                    }
                    break;
                case ConsoleKey.D5:
                    Console.WriteLine("");
                    Console.WriteLine("You can't attack with an Apple!");
                    break;
                case ConsoleKey.D6:
                    Console.WriteLine("");
                    Console.WriteLine("You can't attack with a Golden Key!");
                    break;
                case ConsoleKey.D7:
                    Console.WriteLine("");
                    Console.WriteLine("You can't attack with a Steak!");
                    break;
                default:  Console.WriteLine("Invalid Option Qutting loop");
                         return;

            }
            Console.WriteLine("Choose a weapon!");
            var input2 = Console.ReadKey();
            }

【讨论】：