C++ Date Class: Calculate Differences and Add Days

C++ Date Class with Operator Overloading

The following program defines a date class in C++ that calculates the difference between two dates, adds a number of days to a date, and handles leap years correctly.

Source Code

#include<iostream.h>
#include<conio.h>
#include<process.h>

class date
{
private:
    int flag, day, month, year;
public:
    date(int d, int m, int y)
    {
        day = d, month = m, year = y;
        if (year % 4 == 0)
            flag = 1;
        else
            flag = 0;
    }
    int operator-(date d2);
    date operator+(int n);
    int operator>(date d2);
    friend ostream& operator<<(ostream& out, date d1);
    int return_integer_date(date d1);
};

int a[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int b[13] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

int date::return_integer_date(date d1)
{
    int int_value = d1.day;
    if ((d1.flag == 1) && (d1.month > 2))
    {
        for (int i = 0; i < d1.month; i++)
            int_value = int_value + a[i];
        int_value++;
    }
    else
        for (int i = 0; i < d1.month; i++)
            int_value = int_value + a[i];
    return int_value;
}

int date::operator>(date d2)
{
    int x = 1;
    date d1(day, month, year);
    if (d1.day == d2.day && d1.month == d2.month && d1.year == d2.year)
        return x;
    else if (d1.year > d2.year)
        return x;
    else if (d1.month > d2.month)
        return x;
    else if (d1.day > d2.day)
        return x;
    else
        return 0;
}

int date::operator-(date d2)
{
    int a1, a2, x = 0;
    date d1(day, month, year);
    if (d1.day == d2.day && d1.month == d2.month && d1.year == d2.year)
        return x;
    a1 = return_integer_date(d1);
    a2 = return_integer_date(d2);
    for (int i = d1.year - 1; i > d2.year; i--)
    {
        if (i % 4 == 0)
            x = x + 366;
        else
            x = x + 365;
    }
    if (d1.year == d2.year)
        x = x + (a1 - a2);
    else
    {
        x = x + a1;
        if (d2.year % 4 == 0)
            x = x + (366 - a2);
        else
            x = x + (365 - a2);
    }
    return x;
}

date date::operator+(int n)
{
    date d(day, month, year);
    for (int i = 0; i < n; i++)
    {
        d.day++;
        if (d.year % 4 == 0)
        {
            d.flag = 1;
            if (d.day > b[d.month])
            {
                d.day = 1;
                d.month++;
            }
        }
        else
        {
            d.flag = 0;
            if (d.day > a[d.month])
            {
                d.day = 1;
                d.month++;
            }
        }
        if (d.month > 12)
        {
            d.month = 1;
            d.year++;
        }
    }
    return d;
}

ostream& operator<<(ostream& out, date d1)
{
    out << d1.day << "/" << d1.month << "/" << d1.year;
    return out;
}

void main()
{
    int d, m, y, no_of_days;
    clrscr();
    cout << "Enter a valid date\n";
    cout << "Enter day (dd): ";
    cin >> d;
    cout << "Enter month (mm): ";
    cin >> m;
    cout << "Enter year (yyyy): ";
    cin >> y;
    cout << endl;
    date d1(d, m, y);
    cout << "Enter another date\n";
    cout << "Enter day (dd): ";
    cin >> d;
    cout << "Enter month (mm): ";
    cin >> m;
    cout << "Enter year (yyyy): ";
    cin >> y;
    cout << endl;
    date d2(d, m, y);
    cout << "First date entered: " << d1 << endl << endl;
    cout << "Second date entered: " << d2 << endl << endl;
    if (d1 > d2)
    {
        no_of_days = d1 - d2;
    }
    else
        no_of_days = d2 - d1;
    cout << "The difference between the two dates: ";
    cout << no_of_days << " DAYS" << endl << endl;
    getche();
    cout << "Enter a number: ";
    cin >> no_of_days;
    d1 = d2 + no_of_days;
    cout << "\nThe resulting date from the date " << d2 << " is " << d1 << endl;
    getch();
}

Key Features

• Date difference: Computes the number of days between two dates using the - operator.
• Date comparison: Determines which date is later using the > operator.
• Date addition: Adds a given number of days to a date using the + operator.
• Leap year handling: Accounts for February 29 in leap years.

Notes

This code uses iostream.h, conio.h, and void main(), which are non-standard and deprecated. For modern compilers, use <iostream>, remove conio.h, and use int main().