¿Cómo mostrar por pantalla el tiempo transcurrido?

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

using namespace std;

int main() {
    int day, month, year;
    char date[15];
    int day2, month2, year2;
    char date2[15];

    scanf("%s", date);
    sscanf(date, "%2d/%2d/%4d", &day, &month, &year);

    scanf("%s", date2);
    sscanf(date2, "%2d/%2d/%4d", &day2, &month2, &year2);

    int time = year * 365 * 24 * 60 * 60 + month * 30 * 24 * 60 * 60 + day * 24 * 60 * 60;
    int time2 = year2 * 365 * 24 * 60 * 60 + month2 * 30 * 24 * 60 * 60 + day2 * 24 * 60 * 60;

    int diff = abs(time - time2);
    printf