#include <iostream>
#include <cstdlib>
#include <ctime>    //for the functions time and localtime
using namespace std;

class Time {
public:
	//Declarations for the data members:
	int hour;   //in the range 0 to 23 inclusive
	int minute; //in the range 0 to 59 inclusive
	int second; //in the range 0 to 59 inclusive

	//Declarations for the member functions:
	void print() const; //const member function
	void next(int n);   //non-const member function
	void next();
};

int main()
{
	//Output a fixed time.
	const Time midnight {0, 0, 0};   //hour, minute, second
	midnight.print();
	cout << " is midnight.\n";

	//Ask the operating system for the current time.
	const time_t t {time(nullptr)};
	const tm *const p {localtime(&t)};

	//Output the current time.
	const Time now {p->tm_hour, p->tm_min, p->tm_sec};
	now.print();
	cout << " is the current time.\n";

	//Output the time one second from now.
	Time oneSecLater {now}; //Call the "copy constructor".
	oneSecLater.next();     //Advance one second.
	oneSecLater.print();
	cout << " is one second later.\n";

	//Output the time one minute from now.
	Time oneMinLater {now}; //Call the "copy constructor".
	oneMinLater.next(60);
	oneMinLater.print();
	cout << " is one minute later.\n";

	return EXIT_SUCCESS;
}

void Time::print() const  //This member function can't change the Time object.
{
	cout << (hour < 10 ? "0" : "") << hour << ":"
	     << (minute < 10 ? "0" : "") << minute << ":"
	     << (second < 10 ? "0" : "") << second;
}

void Time::next(int n)    //This member function can change the Time object.
{
	for (int i {0}; i < n; ++i) {
		next(); //Call the other next function, the one with no argument
	}
}

void Time::next()   //Move this Time object one second into the future.
{
	if (++second >= 60) {
		second = 0;
		if (++minute >= 60) {
			minute = 0;
			if (++hour >= 24) {
				hour = 0;
			}
		}
	}
}