gistfile1.hpp

#include <iostream>
#include <ctime> 

using namespace std;

// here's the class. a constructor, the subtraction operator and the date property
class qDate
{
public:
    explicit qDate(time_t aDate);
	long operator-(qDate& other);
	time_t date;
};

// implement the constructor
qDate::qDate(time_t aDate)
{
	date = aDate;
}

// overload subtraction. it's pretty verbose, you could tighten it up, but hopefully obvious enough what's going on.
long qDate::operator-(qDate& other)
{
	time_t thisDate = this->date;
	time_t otherDate = other.date;

	long diffInSeconds;

	if (thisDate > otherDate)
	{
		diffInSeconds = thisDate - otherDate;
	}
	else
	{
		diffInSeconds = otherDate - thisDate;
	}

	long diffInDays = diffInSeconds / 3600 / 24;
	return diffInDays;
}

// let's goooo!
int main() 
{
	// you're going to want to get the date from the user instead of defining it here:
	struct tm a = {0, 0, -1, 25, 9, 109}; /* October 25, 2009 */
	struct tm b = {0, 0, -1, 14, 5, 109}; /* June 14, 2009 */
	time_t x = mktime(&a);
	time_t y = mktime(&b);

	if ((time_t)(-1) != x &&	// if we have valid dates
	    (time_t)(-1) != y)
	{
		// create the dates qbot style!
		qDate qDateX(x);
		qDate qDateY(y);

		// output the dates, for shits and/or giggles
		cout << ctime(&qDateX.date);
		cout << ctime(&qDateY.date);

		// calculate the difference in days
		long difference = qDateX - qDateY;

		// inform the user
		cout << "difference = " << difference << " days" << endl;
	}
	else
	{
		cout << "invalid time format etc" << endl;
	}

	return 0;
}