驗證控制台應用程序中的多個用戶輸入

Question

我是C＃的新手，我想知道如何驗證用戶輸入以滿足以下要求：

• 必須是十進制類型。 如果不是，則應要求用戶輸入一個十進制值。 （我相信我已在下面的代碼中進行了介紹）
• 還必須在特定范圍內（1-1,000,000）。 如果不是，則應要求用戶輸入正確范圍內的數字

考慮到我將有多種用戶輸入以相同方式進行驗證，最有效的方法是什么。

decimal balance;
Console.Write("Starting Balance: $");
while (!decimal.TryParse(Console.ReadLine(), out balance))
{
    Console.Write("Please enter a valid decimal value: $");
}

如下編輯

這個怎么樣？

decimal balance;
Console.Write("Starting Balance: $");
while(true)
{
    if (!decimal.TryParse(Console.ReadLine(), out balance))                
        Console.Write("Please enter a valid decimal value: $");
    else if (balance < 1 || balance > 100)
        Console.Write("Please enter an amount between 1 and 100: ");
    else
        break;                
}
Console.WriteLine("Balance entered is: " + balance.ToString("n"));

return val; 行給了我一個錯誤，所以我把它遺漏了，但是上面的方法似乎起作用了？

Answer 1

我會嘗試類似的東西：

decimal GetUserInput(string inputQuery, decimal min, decimal max)
{
  Console.Write(inputQuery);
  decimal val;
  while(true)
  {
    if(!decimal.TryParse(Console.ReadLine(), out val))
      Console.Write("Please enter a valid decimal value: $");
    else if(val < min || val > max)
      Console.Write("Please enter an amount between " + min + " and " + max + ": $");
    else // the value is a decimal AND it's correct
      break;
  } 
  return val;
}

然后像這樣使用它：

var startingBalance = GetUserInput("Starting Balance: $", 1, 100000);
var endingBalance = GetUserInput("Ending Balance: $", 1, 100000);
//...

如果您的最小值和最大值是固定的，那么您將無法將它們作為參數傳遞並使用固定的檢查。 而且您還可以避免傳遞查詢: $ （如果需要），但是我會留給您

更新

return val行給您一個錯誤的原因是因為您對其進行了內聯（可能是在void returning函數中）。 我正在做的是創建一個函數，因為您指定它需要可重用。

因此，在您的程序中，您需要創建一個單獨的函數...您的程序應如下所示：

class Program
{
    // We're declaring this function static so you can use it without an instance of the class
    // This is a function, so it can be called multiple times, with different arguments
    static decimal GetUserInput(string inputQuery, decimal min, decimal max)
    {
      // Write the argument "inputQuery" to console
      Console.Write(inputQuery);
      decimal val;

      // Loop indefinitely
      while(true)
      {
        // Read from console into a decimal "val"
        if(!decimal.TryParse(Console.ReadLine(), out val))
          // It was not a correct decimal, so write the prompt
          Console.Write("Please enter a valid decimal value: $");
        // It was a correct decimal
        else if(val < min || val > max)
          // But not in range, so write a different prompt
          Console.Write("Please enter an amount between " + min + " and " + max + ": $");
        // It was a decimal and within range
        else
          // so we break the infinite loop and exit after the "}"
          break;

        // If we have got to this point (we didn't hit the "break"),
        // it was either not a decimal or it wasn't within range, 
        // so it'll loop again and ask for a value from console again.
        // The prompt was already written above (in the "ifs")

      } 
      // We got out of the while(true){} loop, so it means we hit "break"
      // above, and that means "val" contains a correct value (decimal and
      // within range), so we return it to the caller
      return val;
    }

    static void Main()
    {
      // Your original code went here, but see how my function is *outside* function Main()

      // You use my function (GetUserInput) here:
      var startingBalance = GetUserInput("Starting Balance: $", 1, 100000);
      var endingBalance = GetUserInput("Ending Balance: $", 1, 100000);

      // Then with the returned values (stored in "startingBalance"
      // and "endBalance"), you can do what you want:
      Console.WriteLine("Starting balance was: " + startingBalance.ToString("n"));
    }
}

我已經對整個程序進行了擺弄，因此您可以在線進行測試並進行更改： https : //dotnetfiddle.net/HiwwIP

Answer 2

如果我是你，我會這樣做：

        bool isInvalid, isOutOfRange;
        decimal balance = 0;
        isOutOfRange = true;
        do
        {
            string input = Console.ReadLine();
            isInvalid = !Decimal.TryParse(input, out balance);
            if (!isInvalid)
            {
                // use balance<=1 if 1 should not be included
                // use balance>=1000000 if 1000000 should not be included
                isOutOfRange = (balance < 1 || balance > 1000000);
            }
            if (isInvalid)
            {
                Console.WriteLine("Please enter a valid decimal value: $");
            }
            else if (isOutOfRange)
            {
                Console.WriteLine("Please enter value between 1 and 1000000: $");
            }

        } while (isInvalid || isOutOfRange);
        Console.WriteLine("{0}, That is a valid value!", balance.ToString());
        Console.ReadKey();

當然，您可以通過消除bool定義並直接調用函數來實現快捷方式； 但是為了清楚起見，我詳細地寫了一下，因為您表示您“很新”。