Shows timer info.

#include <stdio.h>

#include <stdlib.h>

#include <time.h>

#include <sys/time.h>

int

random_two_digit_number() {

  return atoi(buf);

}

typedef struct timer_struct {

  struct timeval then;

} timer_t;

void

start_timer(timer_t *timer) {

  gettimeofday(&timer->then, NULL);

}

long int

end_timer(timer_t *timer) {

  struct timeval now;

  long int delta;

  gettimeofday(&now, NULL);

  delta = (now.tv_sec - timer->then.tv_sec) * 1000000;

  delta += now.tv_usec - timer->then.tv_usec;

  return delta;

}

int

main(int argc, char *argv[]) {

  int guess, number;

  timer_t timer;

  long int delta;

  srand(time(NULL));

  while (1) {

    number = random_two_digit_number();

    printf("Number is %d. Cube root (0 to exit)? ", cube(number));

    start_timer(&timer);

    guess = read_number();

    delta = end_timer(&timer);

    if (guess == 0) {

      exit(0);

    }

    } else {

      printf("Not correct. Number was %d.\n", number);

    }

    if (delta < 1000) {

      printf("Took %ldus\n", delta);

    } else if (delta < 1000000) {

      printf("Took %.1fms\n", delta / 1000.0);

    } else {

      printf("Took %.2fs\n", delta / 1000000.0);

    }

  }

}