The for loop does not work?

#include <iostream>
#include <iomanip>
#include "C1A7E1_MyTime.h"
using namespace std;

MyTime *DetermineElapsedTime(const MyTime *tp1, const MyTime *tp2);
int main()
{
   for (int loop_count = 0; loop_count < 3; loop_count++)
    {
    	
        cout << "Enter time point one, space separated:\n";
        cin >> tm1.hours >> tm1.minutes >> tm1.seconds;
        cout << "Enter time point one, space separated:\n";
        cin >> tm2.hours >> tm2.minutes >> tm2.seconds;
        cout << "entering function!";
        DetermineElapsedTime(const tm1, const tm2)
				 }
    const MyTime tm1 = { 2, 0, 0};
    const MyTime tm2 = { 0, 0, 0};
    MyTime time_dif = *DetermineElapsedTime(&tm1, &tm2);
    cout << "The time elapsed from ";
    cout << setfill('0') << setw(2) << tm1.hours << ":";
    cout << setfill('0') << setw(2) << tm1.minutes << ":";
    cout << setfill('0') << setw(2) << tm1.seconds;
    cout << " to ";
    cout << setfill('0') << setw(2) << tm2.hours << ":";
    cout << setfill('0') << setw(2) << tm2.minutes << ":";
    cout << setfill('0') << setw(2) << tm2.seconds;
    cout << " is ";
    cout << time_dif.hours << ":" << time_dif.minutes << ":" << time_dif.seconds << "\n";
}


C1A7E1_MyTime.h


#ifndef Class_Test_C1A7E1_MyTime_h
#define Class_Test_C1A7E1_MyTime_h
using namespace std;
struct MyTime { int hours, minutes, seconds; }; /* do not change this */

#endif

C1A7E1_DetermineElapsedTime.cpp


#include <iostream>
#include "C1A7E1_MyTime.h"
using namespace std;
MyTime *DetermineElapsedTime(const MyTime *tp1, const MyTime *tp2)
{
    static MyTime return_time;
    MyTime testy1, testy2;
    testy1 = *tp1;
    testy2 = *tp2;
    long time_point_dif;
    time_point_dif = (long(testy1.hours) * 3600 + long(testy1.minutes) * 60 + long(testy1.seconds)) - \
    (long(testy2.hours) * 3600 + long(testy2.minutes) * 60 + long(testy2.seconds));
    return_time.hours = int(time_point_dif / 3600);
    time_point_dif -= return_time.hours * 3600;
    return_time.minutes = int(time_point_dif / 60);
    time_point_dif -= return_time.minutes * 60;
    return_time.seconds = int(time_point_dif);
    return(&return_time);
  
}