Benchmark - Stopping loop iteration

benchmark.cpp

#include <cstdio>
#include <ctime>
#include <sys/time.h>

#define SIZE 1000000001

char str[SIZE];

void with_break(char *str) {
  bool a_found = false;
  for (int i = 0; str[i]; i++) {
    if (str[i] == 'a') {
      a_found = true;
      break;
    }
  }
}

void with_condition(char *str) {
  bool a_found = false;
  for (int i = 0; a_found == false && str[i]; i++) {
    if (str[i] == 'a') {
      a_found = true;
    }
  }
}

void populate(int size) {
  for(int i = 0; i < size; i++) {
    str[i] = i == size/2 ? 'a' : 'b';
  }
  str[size] = NULL;
}

float time_it(void (*fn)(char *)) {
  struct timeval start_time, end_time;
  gettimeofday(&start_time, 0);
  fn(str);
  gettimeofday(&end_time, 0);
  return (end_time.tv_sec - start_time.tv_sec) * 1000.0f + (end_time.tv_usec - start_time.tv_usec) / 1000.0f;
}

int get_size(int iteration) {
  switch (iteration) {
    case 0: return 500;
    case 1: return 1000;
    case 2: return 10000;
    case 3: return 100000;
    case 4: return 1000000;
    case 5: return 10000000;
    case 6: return 50000000;
    case 7: return 100000000;
    case 8: return 500000000;
    case 9: return 1000000000;
  }
  return 0;
}

int main() {
  printf("iteration,with_break,with_condition,percent,elements\n");

  for (int iteration = 0; iteration < 10; iteration ++) {
    int size = get_size(iteration);
    populate(size);
    for (int repetition = 0; repetition < 5; repetition++) {
      float time_break = time_it(with_break);
      float time_condition = time_it(with_condition);
      printf("%d", iteration);
      printf(",%f", time_break);
      printf(",%f", time_condition);
      printf(",%f", (((time_condition - time_break) * 100)/(1.0 * time_break)));
      printf(",%d\n", size);
    }
  }
  return 0;
}