switch语句

问题描述：

嗨，我正在练习程序中的“开关循环”。我正在创建一个代码，用户可以输入整数，在用户输入整数后，它也会显示用户输入的内容。现在我试图在程序要求用户输入通过选择Y/N再次输入号码。我已经将它包含在我的代码中，但如果我在程序第一次输入字符时键入一个整数，程序将执行catch部分。我怎样才能让它，如果用户将键入一个字符，它也将显示消息，“请输入整数：”switch语句

感谢您的帮助我很迷茫在这里的某个地方。

  int enterYourNumber; 
      char shortLetter; 

      try 
      { 
       Console.WriteLine("Please enter the integer: "); 
       enterYourNumber = Convert.ToInt32(Console.ReadLine()); 
       WriteNumber(enterYourNumber); 

       Console.WriteLine("Do you still want to enter a number? Y/N"); 
       shortLetter = Convert.ToChar(Console.ReadLine()); 

       while (shortLetter == 'y' || shortLetter == 'Y') 
       { 
        Console.WriteLine("Please enter the integer: "); 
        enterYourNumber = Convert.ToInt32(Console.ReadLine()); 
        WriteNumber(enterYourNumber); 

        Console.WriteLine("Do you still want to enter a number? Y/N"); 
        shortLetter = Convert.ToChar(Console.ReadLine()); 
       } 

      } 
      catch 
      {           
       Console.WriteLine("Please enter an integer not a character"); 
      } 
     } 

      public static void WriteNumber(int wordValue) 
      { 

      switch (wordValue) 
      { 
       case 1: 
        Console.WriteLine("You have entered number one"); 
        break; 
       case 2: 
        Console.WriteLine("You have entered number two"); 
        break; 
       case 3: 
        Console.WriteLine("You have entered number three"); 
        break; 
       default: 
        Console.WriteLine("You have exceeded the range of number 1-3 "); 
        break; 
      }

======================

这是我做的，我不知道为什么我得到一个错误。新的方法似乎不起作用：

 int enterYourNumber; 
     char shortLetter; 


      do 
     { 
      enterYourNumber = GetNumber(); 
      WriteNumber(enterYourNumber);     
      Console.WriteLine("Do you still want to enter a number? Y/N"); 
      shortLetter = Convert.ToChar(Console.ReadLine()); 
     } 
     while (shortLetter == 'y' || shortLetter == 'Y') 
     { 
      Console.WriteLine("Please enter the integer: "); 
      enterYourNumber = Convert.ToInt32(Console.ReadLine()); 
      WriteNumber(enterYourNumber); 

      Console.WriteLine("Do you still want to enter a number? Y/N"); 
      shortLetter = Convert.ToChar(Console.ReadLine()); 
     } 
    } 



     public static int GetNumber() 
     { 
     bool done = false; 
     int value; 
     while (!done) 
     { 
      Console.WriteLine("Please enter the integer: "); 
     try 
     { 
      value = Convert.ToInt32(Console.ReadLine()); 
      done = true; 
     } 
     catch 
     { 
      Console.WriteLine("Please enter an integer not a character"); 
     } 
     } 
     }

=============

你好比尔，这是你给的例子，似乎我仍然得到一个错误：你可以请代码。再次

public static void Main(string[] args) 
    { 
     int enterYourNumber; 
     char shortLetter; 



     do 
     { 
      enteryourNumber = GetNumber(); 
      WriteNumber(enteryourNumber); 
      Console.WriteLine("Do you still want to enter a number? Y/N"); 
      shortLetter = Convert.ToChar(Console.ReadLine()); 
     } 
     while (shortLetter == 'y' || shortLetter == 'Y'); 
    } 


    public static int GetNumber() 
    { 
     bool done = false; 
     int value; 
     while (!done) 
     { 
      Console.WriteLine("Please enter the integer: "); 
      try 
      { 
       value = Convert.ToInt32(Console.ReadLine()); 
       done = true; 
      } 
      catch 
      { 
       Console.WriteLine("Please enter an integer not a character"); 
      } 

      Console.WriteLine("Please enter the integer: "); 
      enterYourNumber = Convert.ToInt32(Console.ReadLine()); 
      WriteNumber(enterYourNumber); 
      Console.WriteLine("Do you still want to enter a number? Y/N"); 
      shortLetter = Convert.ToChar(Console.ReadLine()); 
     } 
    } 

    public static void WriteNumber(int wordValue) 
    { 

     switch (wordValue) 
     { 
      case 1: 
       Console.WriteLine("You have entered number one"); 
       break; 

      case 2: 
       Console.WriteLine("You have entered number two"); 
       break; 

      case 3: 
       Console.WriteLine("You have entered number three"); 
       break; 

      default: 
       Console.WriteLine("You have exceeded the range of number 1-3 "); 
       break; 
     } 
    } 
}

}

=================

你好这个问题是罗伯特：非常感谢你。这就是我现在所做的，但是如果我输入“N”，它不会退出程序。它仍然问了同样的问题。任何想法：感谢：

public static void Main(string[] args) 
    { 
     int enterYourNumber; 
     char shortLetter; 
     bool validEntry; 



     while (true) 
     { 
      do 
      { 
       Console.WriteLine("Please enter an integer: "); 
       string numberString = Console.ReadLine(); 
       validEntry = int.TryParse(numberString, out enterYourNumber); 
       WriteNumber(enterYourNumber); 
       if (!validEntry) 
       { 
        Console.WriteLine("Entry must be an integer"); 
       } 
      } while (!validEntry); 

      Console.WriteLine("Do you still want to enter a number? Y/N"); 
      shortLetter = Convert.ToChar(Console.ReadLine()); 


     } 
    } 




    public static void WriteNumber(int wordValue) 
    { 
     switch (wordValue) 
     { 
      case 1: 
       Console.WriteLine("You have entered number one"); 
       break; 
      case 2: 
       Console.WriteLine("You have entered numbered two"); 
       break; 
      case 3: 
       Console.WriteLine("You have entered numbered three"); 
       break; 
      default: 
       Console.WriteLine("You have exceeded the range of number 1-3"); 
       break; 
     } 
    } 
}

}

================================= ===

嗨罗伯特和比尔这里是我现在得到的。希望你能提出一些关于如何改进编码的想法。谢谢你的帮助。

 public static void Main(string[] args) 
    { 
     int intEnterYourNumber; 
     char charShortLetter; 
     string strUserInput; 

     do 
     { 
      do 
      { 
       Console.WriteLine("Please enter the integer: "); 
       strUserInput = Console.ReadLine(); 
      } while (!int.TryParse(strUserInput, out intEnterYourNumber)); 
      WriteNumber(intEnterYourNumber); 
      Console.WriteLine("Do you still want to enter a number? Y/N"); 
      charShortLetter = Convert.ToChar(Console.ReadLine().ToUpper()); 
     } while (charShortLetter == 'Y'); 
    } 



    public static void WriteNumber(int wordValue) 
    { 
     switch (wordValue) 
     { 
      case 1: 
       Console.WriteLine("You have entered number one"); 
       break; 
      case 2: 
       Console.WriteLine("You have entered numbered two"); 
       break; 
      case 3: 
       Console.WriteLine("You have entered numbered three"); 
       break; 
      default: 
       Console.WriteLine("You have exceeded the range of number 1-3"); 
       break; 
     } 
    }

答

移动循环内的try/catch块。 Robert Harvey对do/while循环的建议也很好。

int enterYourNumber; 
char shortLetter; 

do 
{ 
     try 
     { 
      Console.WriteLine("Please enter the integer: ");     
      enterYourNumber = Convert.ToInt32(Console.ReadLine());     
      WriteNumber(enterYourNumber); 
     } 
     catch(FormatException) 
     {           
      Console.WriteLine("Please enter an integer not a character"); 
     } 

     shortLetter = '\0'; 
     do 
     { 
      try 
      { 
       Console.WriteLine("Do you still want to enter a number? Y/N");      
       shortLetter = Convert.ToChar(Console.ReadLine()); 
      } 
      catch(FormatException) 
     { 
       Console.WriteLine("Please enter a single character"); 
     } 
     }  
     while (shortLetter == '\0')  
}     
while (shortLetter == 'y' || shortLetter == 'Y') 

} 

     public static void WriteNumber(int wordValue) 
     { 

     switch (wordValue) 
     { 
      case 1: 
       Console.WriteLine("You have entered number one"); 
       break; 
      case 2: 
       Console.WriteLine("You have entered number two"); 
       break; 
      case 3: 
       Console.WriteLine("You have entered number three"); 
       break; 
      default: 
       Console.WriteLine("You have exceeded the range of number 1-3 "); 
       break; 
     }

答

do 
{ 
    Console.WriteLine("Please enter the integer: ");     
    enterYourNumber = Convert.ToInt32(Console.ReadLine());     
    WriteNumber(enterYourNumber);     
    Console.WriteLine("Do you still want to enter a number? Y/N");      
    shortLetter = Convert.ToChar(Console.ReadLine()); 
}     
while (shortLetter == 'y' || shortLetter == 'Y')

感谢罗伯特怎么样，如果用户将输入的第一次一个角色？ – tintincutes 2009-06-14 01:16:14

把这个做/做在你的try/catch中，就像在原始代码中一样。 – 2009-06-14 01:24:15

不幸的是，它并没有让用户在发生异常后回到循环中，这是一个问题。 – billjamesdev 2009-06-14 02:16:00

答

罗伯特是一个开始，但也许我们还是想尝试捕捉...

替换为您的主要功能：

do 
{ 
    enterYourNumber = GetNumber(); 
    WriteNumber(enterYourNumber);     
    Console.WriteLine("Do you still want to enter a number? Y/N"); 
    shortLetter = Convert.ToChar(Console.ReadLine()); 
} 
while (shortLetter == 'y' || shortLetter == 'Y')

，并添加此功能：

public static int GetNumber() { 
    boolean done = false; 
    int value; 
    while (!done) { 
     Console.WriteLine("Please enter the integer: "); 
     try { 
      value = Convert.ToInt32(Console.ReadLine()); 
      done = true; 
     } 
     catch { 
      Console.WriteLine("Please enter an integer not a character"); 
     } 
    } 
}

然后删除您的try catch主要功能。

嗨比尔请看我编辑的答案，看来新方法在这里有问题 – tintincutes 2009-06-14 01:33:36

答

由于您正在学习，您可能还会考虑以不同方式处理错误。
查看SO问题：In C# should try-catch be used for is-numeric testing?了解更多想法和讨论。

答

我觉得你的代码会更容易学习和理解，如果你没有使用异常来测试你的号码。尝试使用int.TryParse（）代替（MSDN上的TryParse()）。的TryParse（）取决于输入的号码是否有效返回真（或假）：

int number; 
bool validEntry = int.TryParse(enterYourNumber, out number); 
if (!validEntry) 
{ 
    Console.WriteLine("Entry must be an integer."); 
}

此外，了解do ... while循环（link）。 do..while循环类似于常规的while循环，除了在计算条件表达式之前执行do-while循环一次。

bool validEntry; 
int enteredNumber; 
do 
{ 
    Console.Write("Please enter the integer: "); 
    string numberString = Console.ReadLine(); 
    validEntry = int.TryParse(numberString, out enteredNumber); 
    if (!validEntry) 
    { 
     Console.WriteLine("Entry must be an integer."); 
    } 
} while (!validEntry);

裹在另一个while循环，整个事情（“你还是要输入数字（Y/N）？”），你就大功告成了。

享受，

罗伯特C. Cartaino

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