Advancing day by day until it matches a second date

Hi, I need to write a function that advances a date one day at a time until it matches a second date. I coded everything else, just having problems with this part of the problem.

One function is passed two dates and then a function within that function does the advancing one day at a time, keeping count along the way and then returning the number of days in between the two dates.

Please help!! My trouble is with the functions difference and advance_date.

Code:

---

#include <iostream>
using namespace std;

class Date
{
  public:
        Date() {month=1; day=1; year=1900;};
          //default constructor; initializes the date to 1/1/1900
        Date(int m, int d, int y);
          //constructor; initializes the date that is entered in
        void set_date(int m, int d, int y);
          //allows the user to enter in the date
        void display_date();
          //prints the date with the month in word format; i.e. 1/1/2000 will print out January 1, 2000
        void advance_date();
          //advances the date by 1 day
        int get_day();
          //returns the value of the invoking day
        int get_month();
          //returns the value of the invoking month
        int get_year();
          //returns the value of the invoking year
        bool is_less_than(Date&);
          //returns true if the original invoking date is less than the one passed in, and false otherwise
        bool is_equal(Date&);
          //returns true if the original invoking date is equal to the one passed in, and false otherwise

  private:
        int month;
        int day;
        int year;
};

int difference(int earlier_day, int earlier_month, int earlier_year, int later_day, int later_month, int later_year,
                          Date date1, Date date2);

int main()
{
        Date first_date;
        Date second_date;
        Date earlier_date;
        Date later_date;
        int month1, day1, year1, month2, day2, year2;
        int m1, d1, y1, m2, d2, y2;
        int days_apart;

        cout << "Please enter a Date in the following format: xx/xx/xxxx\n";
        month1 = first_date.get_month();
        day1 = first_date.get_day();
        year1 = first_date.get_year();
        first_date.set_date(month1, day1, year1);

        cout << "First Date is: ";
        first_date.display_date();

        cout << "Please enter a second Date in tbe following format: xx/xx/xxxx\n";
        month2 = second_date.get_month();
        day2 = second_date.get_day();
        year2 = second_date.get_year();
        second_date.set_date(month2, day2, year2);

        cout << "Second Date is: ";
        second_date.display_date();
       
        if (first_date.is_equal(second_date))
        {
          cout << "The first date is the same as the second date.\n";
        }
        else if (first_date.is_less_than(second_date))
        {
          earlier_date = first_date;
          later_date = second_date;
          cout << "The first date is earlier than the second date.\n";
          d1 = day1;
          m1 = month1;
          y1 = year1;
          d2 = day2;
          m2 = month2;
          y2 = year2;
        }
        else
        {
          earlier_date = second_date;
          later_date = first_date;
          cout << "The first date is later than the second date.\n";
          d1 = day2;
          m1 = month2;
          y1 = year2;
          d2 = day1;
          m2 = month1;
          y2 = year1;
        }

        days_apart = difference(d1, m1, y1, d2, m2, y2, earlier_date, later_date);
        cout << "The two days are " << days_apart << "days apart.\n";
       
        return 0;
}

int Date::get_month()
{
        char slash; //reads in the forward slash between mm/dd/yyyy
        int month;
        cin >> month >> slash;
        return month;
}

int Date::get_day()
{
        char slash;
        int day;
        cin >> day >> slash;
        return day;
}

int Date::get_year()
{
        int year;
        cin >> year;
        return year;
}

void Date::set_date(int m, int d, int y)
{
        month = m;
        day = d;
        year = y;
        return;
}

void Date::display_date()
{
        switch(month)
        {
          case 1: cout << "January ";
            break;
          case 2: cout << "February ";
            break;
          case 3: cout << "March ";
            break;
          case 4: cout << "April ";
            break;
          case 5: cout << "May ";
            break;
          case 6: cout << "June ";
            break;
          case 7: cout << "July ";
            break;
          case 8: cout << "August ";
            break;
          case 9: cout << "September ";
            break;
          case 10: cout << "October ";
            break;
          case 11: cout << "November ";
            break;
          case 12: cout << "December ";
            break;
        }       
        cout << day << ", " << year << endl;
        return;
}


bool Date::is_equal(Date& second_date)
{
        if ((month == second_date.month) && (day == second_date.day) && (year == second_date.year))
          return true;
        else
          return false;
}

bool Date::is_less_than(Date& second_date)
{
        if (year < second_date.year)
        {
          return true;
        }
        else if (month < second_date.month)
        {
          return true;
        }
        else if (day < second_date.day)
        {
          return true;
        }
        else
        {
          return false;
        }
}

int difference(int earlier_day, int earlier_month, int earlier_year, int later_day, int later_month,
                          int later_year, Date date1, Date date2)
{
        int diff_days = 0;

        while ((earlier_day != later_day) || (earlier_month != later_month) || (earlier_year != later_year))
        {
          date1.advance_date();
          diff_days++;
        }
        return diff_days;
}

void Date::advance_date()
{
        int months[12];
        int max_no_months = 12;
        int days_in_month[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
}

---

I guess the biggest problem with your advance_date function is that it's missing.

It might help to think of it odometer-style -- change the day, until it wraps around and then change the month, etc.