// File: whattime.cxx
// Michael Main - Jan 28, 2003
// This program prints the time in the current time
// zone. The constant ZONE_ADJUST should be set to
// the number of seconds that the current time zone
// differs from GMT.  The constant ZONE_NAME should
// be set to the current time zone name.  There are
// other ways to write this program that will work
// correctly in any time zone, but we haven't yet
// learned about those techniques.
//
// Note: The time(0) function used in this program
// returns the number of seconds that have passed
// since the start of 1970, using GMT. But this time
// function will fail to work sometime in 2038 because
// the long data type is not big enough to hold the
// accumulated number of seconds.  The exact time of
// doom is Jan 19, 2038 at 3:14:08am GMT.  There are
// other time systems that count from 1900 with a data
// type that will overflow at 6:28:17am on Feb 7, 2035.

#include <ctime>     // Provides the time function
#include <iostream>  // Provides cout
#include <string>    // Provides the string class
using namespace std;

const long SECONDS_PER_MINUTE = 60;
const long SECONDS_PER_HOUR = 60 * SECONDS_PER_MINUTE;
const long SECONDS_PER_DAY = 24 * SECONDS_PER_HOUR;
const long ZONE_ADJUST = -7 * SECONDS_PER_HOUR;
const string ZONE_NAME = "Mountain Time";

void get_time
(int& hour, int& minute, int& second, char& a_or_p);
// This function sets the three reference parameters
// (hour, minute and second) to the time in the
// current time zone using a usual 12-hour clock.
// The reference parameter a_or_p is set to 'a' if the
// time is before noon and to 'p' on or after noon.

int main( )
{ 
    int hour, minute, second;
    char a_or_p;
    
    get_time(hour, minute, second, a_or_p);
    
    cout << hour;
    cout << ":";
    if (minute < 10)
	cout << "0";
    cout << minute;
    cout << ":";
    if (second < 10)
	cout << "0";
    cout << second;
    cout << a_or_p << "m " << ZONE_NAME << endl;    

    return 0;
}

void get_time
(int& hour, int& minute, int& second, char& a_or_p)
{
    long many_seconds;

    many_seconds =
	(time(0) + ZONE_ADJUST) % SECONDS_PER_DAY;
    hour = int(many_seconds / SECONDS_PER_HOUR);
    if (hour >= 12)
    {
	a_or_p = 'p';
	if (hour > 12)
	{   // Change 13 to 1pm, 14 to 2pm...
	    hour = hour - 12;
	}
    }
    else
    {
	a_or_p = 'a';
	if (hour == 0)
	{   // Change the first hour of the day to 12am
	    hour = 12;
	}
    }
    many_seconds = many_seconds % SECONDS_PER_HOUR;
    minute = int(many_seconds / SECONDS_PER_MINUTE);
    second = int(many_seconds % SECONDS_PER_MINUTE);
}