Date Difference program in c

const int monthDays[12] = {31, 28, 31, 30, 31, 30,

                           31, 31, 30, 31, 30, 31};

int countLeapYears(Date d)

{

    int years = d.year;

  

    // Check if the current year needs to be considered

    // for the count of leap years or not

    if (d.month <= 2)

        years--;

  

    return years / 4 - years / 100 + years / 400;

}

int difference_in_dates(Date *date1, Date *date2)

{

  

    long int n1 = date1->year*365 + date1->day;

  

    for (int i=0; i<date1->month - 1; i++)

        n1 += monthDays[i];

  

    n1 += countLeapYears(date1);

  

    long int n2 = date2->year*365 + date2->day;

    for (int i=0; i<date2->month - 1; i++)

        n2 += monthDays[i];

    n2 += countLeapYears(date2);

  

    // return difference between two counts

    return (n2 - n1);

}