C++将变量传递给类到函数

Question

我有一个类“Month”，它具有无效的成员函数和无效的参数传递。我需要重载构造函数(我认为)，但编译器不喜欢我的尝试。

class Month
{
public:
    Month(char firstLetter, char secondLetter, char thirdLetter);    //?
    Month::Month(int m) : month(m) {}  //Want above ^ to look like this
    Month();
    void outputMonthNumber();
    void outputMonthLetters();
    //~Month();   // destructor
private:
    int month;
};
void Month::outputMonthNumber()
{
  if (month >= 1 && month <= 12)
    cout << "Month: " << month << endl;
  else
    cout << "Not a real month!" << endl;
}
void Month::outputMonthLetters()
{
    const char * monthNames[] = {
        "Jan","Feb","Mar","Apr","May","Jun",
        "Jul","Aug","Sep","Oct","Nov","Dec"
    };

    const char * output = "The number is not a month!";
    if (month >= 1 && month <= 12)
        output = monthNames[month - 1];

    cout << output;
}

就像输出月份数字的方式一样，我正在尝试为 outputMonthNumber 做同样的事情，但我无法理解它。

int main(void)
{
    int num;
    char firstLetter, secondLetter, thirdLetter;
    cout << "give me a number between 1 and 12 and I'll tell you the month name: ";
    cin >> num;
    Month myMonth(num);
    myMonth.outputMonthLetters();
    cout << endl << "Give me a 3 letter month and I'll give you the month #: ";
    cin >> firstLetter >> secondLetter >> thirdLetter;
    /*===How would I pass the parameters to the class?===*/
        //Month herMonth(firstLetter, secondLetter, thirdLetter);
        //herMonth.outputMonthNumber();
}

类的所有成员函数都传递void参数。我知道如何通过一个，但我似乎无法让它正确重载。

Answer 1

这样做:

class Month
{
public:
    Month(char firstLetter, char secondLetter, char thirdLetter) :
        first(firstLetter),second(secondLetter),third(thirdLetter)
    {
       const char * monthNames[] = {
        "Jan","Feb","Mar","Apr","May","Jun",
        "Jul","Aug","Sep","Oct","Nov","Dec"
       };
       for ( int i = 0 ; i < 12 ; i++ )
          if ( monthNames[i][0] == first && monthNames[i][1] == second && monthNames[i][2] == third )
              month = i + 1;
    }
    Month::Month(int m) : month(m) {}  //Want above ^ to look like this
    Month();
    void outputMonthNumber();
    void outputMonthLetters();
    //~Month();   // destructor
private:
    int month;
    char first;
    char second;
    char third;
};