 C Program to Calculate Difference Between Two Time Periods

# C Program to Calculate Difference Between Two Time Periods

#### In this example, you will learn to calculate the difference between two time periods using a user-defined function.

To understand this example, you should have the knowledge of the following C programming topics:

## Calculate Difference Between Two Time Periods

``````#include <stdio.h>
struct TIME {
int seconds;
int minutes;
int hours;
};

void differenceBetweenTimePeriod(struct TIME t1,
struct TIME t2,
struct TIME *diff);

int main() {
struct TIME startTime, stopTime, diff;

printf("Enter the start time. \n");
printf("Enter hours, minutes and seconds: ");
scanf("%d %d %d", &startTime.hours,
&startTime.minutes,
&startTime.seconds);

printf("Enter the stop time. \n");
printf("Enter hours, minutes and seconds: ");
scanf("%d %d %d", &stopTime.hours,
&stopTime.minutes,
&stopTime.seconds);

// Difference between start and stop time
differenceBetweenTimePeriod(startTime, stopTime, &diff);
printf("\nTime Difference: %d:%d:%d - ", startTime.hours,
startTime.minutes,
startTime.seconds);
printf("%d:%d:%d ", stopTime.hours,
stopTime.minutes,
stopTime.seconds);
printf("= %d:%d:%d\n", diff.hours,
diff.minutes,
diff.seconds);
return 0;
}

// Computes difference between time periods
void differenceBetweenTimePeriod(struct TIME start,
struct TIME stop,
struct TIME *diff) {
while (stop.seconds > start.seconds) {
--start.minutes;
start.seconds += 60;
}
diff->seconds = start.seconds - stop.seconds;
while (stop.minutes > start.minutes) {
--start.hours;
start.minutes += 60;
}
diff->minutes = start.minutes - stop.minutes;
diff->hours = start.hours - stop.hours;
}``````

Output

```Enter the start time.
Enter hours, minutes and seconds: 13
34
55
Enter the stop time.
Enter hours, minutes and seconds: 8
12
15

Time Difference: 13:34:55 - 8:12:15 = 5:22:40
```

In this program, the user is asked to enter two time periods and these two periods are stored in structure variables startTime and stopTime respectively.

Then, the function `differenceBetweenTimePeriod()` calculates the difference between the time periods. The result is displayed from the `main()` function without returning it (using call by reference technique).