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

#define micro_second_multiplier 1000000
#include <sys/time.h> //for gettimeofday

#include<sys/times.h>
#include <sys/resource.h> 

void work()
{
    //Work to be timed
    for (int ii=0; ii<10; ii++)
    {
	for (int i=0; i<10000000; i++)
	{
	    int j=i*i;
	}
    }
    // end work
}

void t1()
{
    clock_t start, end;
    start = clock();
    work();
    end = clock();
    float cpu_time_used = ((float) (end - start)) / CLOCKS_PER_SEC;
    printf("T1: %10.6f\n", cpu_time_used );
}

void t2()
{
    struct timeval begin, end;
    gettimeofday(&begin, NULL);
    work();
    gettimeofday(&end, NULL);
    float interval=(float)(end.tv_sec*micro_second_multiplier+end.tv_usec - begin.tv_sec*micro_second_multiplier-begin.tv_usec); 
    printf("T2: %10.2f\n", interval );
}


double t2d(struct rusage buf)
{
    return (double)(buf.ru_utime.tv_sec + (double) buf.ru_utime.tv_usec / (double) CLOCKS_PER_SEC); 
}
void t4()
{
    struct rusage buf; 
    getrusage(RUSAGE_SELF, &buf);
    double startt=t2d(buf);
    work();
    getrusage(RUSAGE_SELF, &buf);
    double endt = t2d(buf);
    printf("T4 %10.6f\n", (endt-startt));
}

int main(void)
{
    for (int i=0; i<5; i++)
    {
	t1();
	t2();
	t4();
    }
}