How to compare two objects (the calling object and the parameter) in a class?

Question

I am writing a "Date" class for an assignment and I am having trouble doing one the of the functions.

This is the header file for the class.

class Date
{
public:
Date();                                  // Constructor without parameters
Date(int m, int d, int y); // Constructor with parameters.

// accessors
int GetMonth();               // returns the size of the diamond
int GetDay();
int GetYear();

// mutators
bool Set(int m, int d, int y);
bool SetFormat(char f);

// standard input and output routines
void Input();             
void Show();              
void Increment(int numDays = 1);                 
int Compare(const Date& d);     

private:
int month,                    // month variables
    day,                 // day variable
    year;               // year variable
char format;
};

The member function I am trying to make is the int Compare(const Date& d) function. I need this function to compare two Date objects (the calling object and the parameter), and should return: -1 if the calling object comes first chronologically, 0 if the objects are the same date, and 1 if the parameter object comes first chronologically.

I have tried doing a simple if statement with the == operator but I get errors.

  if (d1 == d2)
     cout << "The dates are the same";
     return (0);

After the objects are created, the function should be called like this d1.Compare(d2)

Thank you in advance!

Answer 1

into the class's public area

bool operator==(const Date& rhs) const {
    return
       year == rhs.year
       && month == rhs.month
       && day == rhs.day
    ;
}