prob66.c

//program to calculate difference between two time period
#include<stdio.h>
struct TIME
{
    int second;
    int minute;
    int hour;
};
void differenceBetweenTimePeriod(struct TIME t1,struct TIME t2,struct TIME *diff);
//computer difference between time period
void differenceBetbeenTimePeriod(struct TIME start,struct TIME stop,struct TIME *diff){
    while (stop.second>start.second)
    {
        --start.minute;
        start.second+=60;
    }
    diff->second=start.second-stop.second;
    while (stop.minute>start.minute)
    {
        --start.hour;
        start.minute+=60;
    }
    diff->second=start.second-stop.second;
    while (stop.minute>start.minute)
    {
        --start.hour;
        start.minute+=60;
    }
    diff->minute=start.minute-stop.minute;
    diff->hour=start.hour-stop.hour;
}
int main(){
    struct TIME startTime,stopTime,diff;
    printf("enter the start time.\n");
    printf("enter hours, minutes and seconds: ");
    scanf("%d %d %d", &startTime.hour,&startTime.minute,&startTime.second);
    printf("enter the stop time.\n");
    printf("enter hours,minuts and secods: \n");
    scanf("%d %d %d", &stopTime.hour,&stopTime.minute,&stopTime.second);
    //difference between start and stop
    differenceBetweenTimePeriod(startTime,stopTime,&diff);
    printf("time difference : %d %d %d-",startTime.hour,startTime.minute,startTime.second);
    printf("%d:%d:%d\n",stopTime.hour,stopTime.minute,stopTime.second);
    printf("=%d:%d:%d\n",diff.hour,diff.minute,diff.second);
    return 0;
}