CS 33: one solution to the time-difference problem

timediff.c

#include <stdio.h>
#include <stdlib.h>

// Prompts the user for two times (in hh:mm format) and outputs 
// the difference between them, assuming they're on the same day.
// No error checking.
int main() {
    int hours1, minutes1, hours2, minutes2;
    int hourDiff, minuteDiff;

    printf("Enter the first time: ");
    scanf("%d:%d", &hours1, &minutes1);

    printf("Enter the second time: ");
    scanf("%d:%d", &hours2, &minutes2);

    if (hours1 == hours2 && minutes1 == minutes2) {
        printf("There is no difference between the times.\n");
        return 0;
    }
  
    if (hours1 > hours2) {
        hourDiff = hours1 - hours2;
        minuteDiff = minutes1 - minutes2; // might be < 0, but right order
    } else if (hours2 > hours1) {
        hourDiff = hours2 - hours1;
        minuteDiff = minutes2 - minutes1;
    } else { // hours are equal
        hourDiff = 0;
        minuteDiff = abs(minutes2 - minutes1);
    }

    if (minuteDiff < 0) {
        hourDiff--;
        minuteDiff += 60;
    }

    printf("The difference between the times is");

    if (hourDiff == 0)
        ;
    else if (hourDiff == 1)
        printf(" 1 hour");
    else
        printf(" %d hours", hourDiff);

    if (hourDiff && minuteDiff)
        printf(" and");

    if (minuteDiff == 0)
        printf(".\n");
    else if (minuteDiff == 1)
        printf(" 1 minute.\n");
    else
        printf(" %d minutes.\n", minuteDiff);

    return 0;
}