// airtime.cpp
// class models time data type
// overloads operators

#include "airtime.h"

airtime airtime::operator + (const airtime& right) const //overloaded + operator
{	int temphrs = hours + right.hours;	         // add data
	int tempmins = minutes + right.minutes;
        if(tempmins >= 60)				 //check for carry
        {	temphrs++;
		tempmins -= 60;
        }
    	return airtime(temphrs, tempmins); 		// return unnamed temporary object
}
                                                              
int airtime::operator < (const airtime& right) const	// overloaded < operator
{	if(hours < right.hours)
    		return 1;
	if(hours == right.hours && minutes < right.minutes)
        	return 1;
	return 0;
}

airtime& airtime::operator += (const airtime& right)
{	hours += right.hours;           // add argument to us
	minutes += right.minutes;
	if(minutes >= 60)               // check for carry
	{	hours++;
		minutes -= 60;
	}
	return *this;			// return by reference
}

airtime& airtime::operator++ ()		// overloaded prefix ++ operator
{	++minutes;
    	if(minutes >= 60)
    	{	++hours;
        	minutes -= 60;
    	}
    	return *this;			// return object by reference
}

airtime airtime::operator++ (int)	// overloaded postfix ++ operator
{	airtime temp(hours, minutes);	// save original value
    	++minutes;			// increment this object
    	if(minutes >= 60)
    	{	++hours;
        	minutes -= 60;
    	}
    	return temp;			// return old original value
}

airtime airtime::operator-() const	// negation operator
{					// unary minus
	return airtime(-hours, minutes);
}
                                 
airtime airtime::operator-(const airtime& right) const	 // subtraction operator
{	int thours = hours - right.hours;
    	int tminutes = minutes - right.minutes;
    	if (tminutes < 0)
    	{	tminutes += 60;
        	thours -=1;
    	}
    	return airtime(thours, tminutes);
}

istream& operator >> (istream& s, airtime& t) 	// get time
{	char dummy;				// from user
    	cout <<"\nEnter time (format 12:59): "; // using
	s >> t.hours >> dummy >> t.minutes;	// overloaded >> operator
    	return s;
}

ostream& operator << (ostream& s, const airtime& t) 
{	s << t.hours << ':' << t.minutes;
	return s;
}