prog.9.6.c

// Program to illustrate arrays of structures

#include <stdio.h>

struct time
{
	int hour;
	int minutes;
	int seconds;
};

int main (void)
{
	struct time timeUpdate (struct time now);
	struct time testTimes[5] = {
		{ 11, 59, 59 }, { 12, 0, 0 }, { 1, 29, 59 },
		{ 23, 59, 59 }, { 19, 12, 27 }
	};
	int i;

	for ( i = 0; i < 5; ++i ) {
		printf ("Time is %.2i:%.2i:%.2i", testTimes[i].hour,
				testTimes[i].minutes, testTimes[i].seconds);

		testTimes[i] = timeUpdate (testTimes[i]);

		printf (" ...one second later it's %.2i:%.2i:%.2i\n",
				testTimes[i].hour, testTimes[i].minutes, testTimes[i].seconds);
	}

	return 0;
}

// Function to update the time by one second

struct time timeUpdate (struct time now)
{
	++now.seconds;

	if ( now.seconds == 60 ) {		// next minute
		now.seconds = 0;
		++now.minutes;

		if ( now.minutes == 60 ) {	// next hour
			now.minutes = 0;
			++now.hour;

			if ( now.hour == 24 )	// midnight
				now.hour = 0;
		}
	}

	return now;
}