如何減少此函式中的遞回

無法弄清楚如何防止此函式中的遞回，有什么建議或建議嗎？我已經嘗試了幾個我自己的解決方案，但是如果輸入錯誤并重復輸入，就會遇到程式崩潰的錯誤。提前致謝，DK。

static void CheckPlayerInput()
{
    // gets the character entered (as a char)
    cin >> input;

    //check is actually a char
    if (cin.fail())
    {
        //more recursion, could cause issues, could you find another way?
        cout << "Invalid character, try again!" << endl;
        CheckPlayerInput();
    }

    //converts char to upper case
    input = toupper(input);

    //check the input character
    // maps the input keys to the grid reference
    //calling the FillSquare method
    switch (input)
    {
    case '1': FillSquare(0, 0); break; //top-left
    case '2': FillSquare(0, 1); break; //top-centre
    case '3': FillSquare(0, 2); break; //top-right
    case '4': FillSquare(1, 0); break; //middle-left
    case '5': FillSquare(1, 1); break; //middle-centre
    case '6': FillSquare(1, 2); break; //middle-right
    case '7': FillSquare(2, 0); break; //bottom-left
    case '8': FillSquare(2, 1); break; //bottom-centre
    case '9': FillSquare(2, 2); break; //bottom-right
        //IF NOT ANY OF THE ABOVE
    default:
    {
        //more recursion, could cause issues
        //
        cout << "Invalid character, try again!" << endl;
        CheckPlayerInput();
    }
    break;
    }

}

uj5u.com熱心網友回復：

改用do while回圈

static void CheckPlayerInput()
{
    bool invalid = false;
    do
    {
        invalid = false;
        // gets the character entered (as a char)
        cin >> input;
...
        default:
        {
            //more recursion, could cause issues
            //
            cout << "Invalid character, try again!" << endl;
            invalid = true;
        }
        break;
      }
    }
    while(invalid);
}

只要輸入無效，while回圈就會重復

uj5u.com熱心網友回復：

我想有很多不同的方法來實作它。以下可能是我的方法。

筆記：

• 填充正方形感覺像是一項專門的任務，因此應該在它自己的功能內。
• 也許您應該使用非靜態/非全域方法，而是使用物件。
• 您的方法CheckPlayerInput不檢查輸入。相反，它正在處理它。

static bool 
_fillSquare(char type)
{
    switch (type)
    {
    case '1': FillSquare(0, 0); break; //top-left
    case '2': FillSquare(0, 1); break; //top-centre
    case '3': FillSquare(0, 2); break; //top-right
    case '4': FillSquare(1, 0); break; //middle-left
    case '5': FillSquare(1, 1); break; //middle-centre
    case '6': FillSquare(1, 2); break; //middle-right
    case '7': FillSquare(2, 0); break; //bottom-left
    case '8': FillSquare(2, 1); break; //bottom-centre
    case '9': FillSquare(2, 2); break; //bottom-right

    default : return false;
    }
    
    return true;
}


// this method does not `check` the player input, but it
// `processes` it. The name should reflect that.
static void 
processPlayerInput()
{
   // try to retrieve and process input until 
   //  a valid input was given

   while (true)
   {
      cin >> input;                
      
      if (!cin.fail ())
         continue;
      
      input = toupper(input);
      bool success = _fillSquare(input);
      if (!success)
      {
         cout << "Invalid character, try again!" << endl;
         continue;
      }
      
      return;           
   }
}

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