C++ 类 : Passing a parameter

Question

我只是在学习类(class)，所以我正在尝试一些基本的东西。我有一个名为 Month 的类，如下所示。对于我的第一个测试，我想提供从 1 到 12 的数字并输出月份的名称，即。 1 = 一月。

class Month
{
public:
    Month (char firstLetter, char secondLetter, char thirdLetter);    // constructor
    Month (int monthNum);
    Month();
    void outputMonthNumber();
    void outputMonthLetters();
    //~Month();   // destructor
private:
    int month;
};
Month::Month()
{
    //month = 1; //initialize to jan
}
void Month::outputMonthNumber()
{
  if (month >= 1 && month <= 12)
    cout << "Month: " << month << endl;
  else
    cout << "Not a real month!" << endl;
}

void Month::outputMonthLetters()
{
  switch (month)
    {
    case 1:
      cout << "Jan" << endl;
      break;
    case 2:
      cout << "Feb" << endl;
      break;
    case 3:
      cout << "Mar" << endl;
      break;
    case 4:
      cout << "Apr" << endl;
      break;
    case 5:
      cout << "May" << endl;
      break;
    case 6:
      cout << "Jun" << endl;
      break;
    case 7:
      cout << "Jul" << endl;
      break;
    case 8:
      cout << "Aug" << endl;
      break;
    case 9:
      cout << "Sep" << endl;
      break;
    case 10:
      cout << "Oct" << endl;
      break;
    case 11:
      cout << "Nov" << endl;
      break;
    case 12:
      cout << "Dec" << endl;
      break;
    default:
      cout << "The number is not a month!" << endl;
    }
}

这是我有问题的地方。我想将“num”传递给 outputMonthLetters 函数。我该怎么做呢？该函数是无效的，但必须有某种方法可以将变量放入类中。我必须公开“月”变量吗？

int main(void)
{
    Month myMonth;
    int num;
    cout << "give me a number between 1 and 12 and I'll tell you the month name: ";
    cin >> num;
    myMonth.outputMonthLetters();
}

Answer 1

你可能想要做的是这样的:

int num;
cout << "give me a number between 1 and 12 and I'll tell you the month name: ";
cin >> num;
Month myMonth(num);
myMonth.outputMonthLetters();

请注意，只有在需要时才声明 myMonth，并且在您确定要查找的月份编号后调用采用月份编号的构造函数。